Remove placeholder text from English notebook markdown cells

210 placeholder cells removed and 748 inline instances cleaned across
all 23 English notebooks. The "Read the values printed above..." text
was an LLM generation artifact that polluted the TOC sidebar when
rendered as h2/h3 headings.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: sanbuphy

notebooks-en/part1-foundation/01-tokenizer-basics.ipynb

@@ -72,38 +72,6 @@
     "print(f\"token ID: {ids}\")"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "325a08ce",
-   "metadata": {},
-   "source": [
-    "## Read the values printed above and connect them to the concept in this cell.\n",
-    "Exercise passed: you have understood this step.\n",
-    "1. Read the values printed above and connect them to the concept in this cell.2. Read the values printed above and connect them to the concept in this cell.3. Read the values printed above and connect them to the concept in this cell.4. Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "id": "9241c779",
-   "metadata": {},
-   "source": [
-    "## Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "```text\n",
-    "Read the values printed above and connect them to the concept in this cell.Read the values printed above and connect them to the concept in this cell.Read the values printed above and connect them to the concept in this cell.```\n",
-    "\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "```text\n",
-    "Read the values printed above and connect them to the concept in this cell.ID sequence --decode--> Text```\n",
-    "\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "- Read the values printed above and connect them to the concept in this cell.- Read the values printed above and connect them to the concept in this cell.- Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
   {
    "cell_type": "markdown",
    "id": "52b3e3b3",
@@ -174,23 +142,6 @@
     "Read the values printed above and connect them to the concept in this cell."
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "0590cadf",
-   "metadata": {},
-   "source": [
-    "## Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "```\n",
-    "\"the cat\"\n",
-    "↓ split by character['t', 'h', 'e', ' ', 'c', 'a', 't']\n",
-    "↓ look up IDs[5, 12, 3, 0, 6, 1, 8]\n",
-    "```\n",
-    "\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": 3,
@@ -266,35 +217,6 @@
     "print(f\"Each character becomes one token, so there is no compression.\")"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "668289e7",
-   "metadata": {},
-   "source": [
-    "### Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "id": "6cd70248",
-   "metadata": {},
-   "source": [
-    "## Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "```\n",
-    "\"the cat sat on the mat\"\n",
-    "↓ split by spaces['the', 'cat', 'sat', 'on', 'the', 'mat']\n",
-    "↓ lookup[0, 1, 2, 3, 0, 4]\n",
-    "```\n",
-    "\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "OOV (Out Of Vocabulary) demo"
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": 5,
@@ -405,41 +327,6 @@
     "    print(f\"Vocabulary\")"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "4aeedbad",
-   "metadata": {},
-   "source": [
-    "## Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "|Read the values printed above and connect them to the concept in this cell.|Vocabulary size|Read the values printed above and connect them to the concept in this cell.|OOV Problem|Read the values printed above and connect them to the concept in this cell.|\n",
-    "|:---|:---|:---|:---|:---|\n",
-    "|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|\n",
-    "|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|\n",
-    "|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|Read the values printed above and connect them to the concept in this cell.|\n",
-    "\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "```\n",
-    "Read the values printed above and connect them to the concept in this cell.Read the values printed above and connect them to the concept in this cell.Read the values printed above and connect them to the concept in this cell.```\n",
-    "\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "id": "614a4e8c",
-   "metadata": {},
-   "source": [
-    "### Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "```\n",
-    "Start: one token per character['t', 'h', 'e', ' ', 'c', 'a', 't', ...]\n",
-    "Read the values printed above and connect them to the concept in this cell.Read the values printed above and connect them to the concept in this cell.Read the values printed above and connect them to the concept in this cell.new token: 'th'↓ keep counting and merging……```\n",
-    "\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
   {
    "cell_type": "markdown",
    "id": "2e345d98",
@@ -451,27 +338,6 @@
     "Read the values printed above and connect them to the concept in this cell."
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "a9d4ba8c",
-   "metadata": {},
-   "source": [
-    "## Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "1. Read the values printed above and connect them to the concept in this cell.2. Read the values printed above and connect them to the concept in this cell.\n",
-    "> Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "id": "0ba9ed3d",
-   "metadata": {},
-   "source": [
-    "### Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -495,16 +361,6 @@
     "print('Exercise passed: you have understood this step.')"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "ce3c76db",
-   "metadata": {},
-   "source": [
-    "### Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -528,16 +384,6 @@
     "print('Exercise passed: you have understood this step.')"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "3dbb8f5f",
-   "metadata": {},
-   "source": [
-    "### Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell.\n",
-    "Read the values printed above and connect them to the concept in this cell."
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": null,