Fix github recipe: document required token scopes and cap comments at 75

Two datasets in this recipe cannot load with the token the README describes,
and one param is silently clamped by the runtime.

1. spiceai.stargazers and apache.members select the user 'email' field
   (connector-github stargazers.rs / members.rs), which GitHub only returns
   for tokens carrying 'read:user' or 'user:email'. A token with just 'repo'
   — all the prerequisite implies — fails both datasets at load. Spell out
   the scopes the recipe actually needs.

2. github_max_comments_fetched was set to 100, above the connector's hard cap
   of 75 (MAX_COMMENTS_FETCHED in connector-github/src/lib.rs). The runtime
   clamps it and logs a warning, so the configured value never took effect.
   Set it to the real maximum.

Also corrects a 'Setp 2.' typo.

Author: Claude

github/README.md

@@ -9,6 +9,14 @@ This recipe will use the [spiceai/spiceai](https://github.com/spiceai/spiceai) r
 - Spice is installed (see the [Getting Started](https://docs.spiceai.org/getting-started) documentation).
 - GitHub personal access token, [Learn more](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens#creating-a-personal-access-token-classic) how to create one.
 
+  Grant the token both of these scopes:
+
+  - `repo` — for the `files`, `issues`, `pulls`, and `commits` datasets.
+  - `read:user` (or `user:email`) — the `stargazers` and `members` datasets select
+    the user `email` field, which GitHub only returns for tokens with one of these
+    scopes. Without it those two datasets fail to load with `Your token has not
+    been granted the required scopes to execute this query`.
+
   [![Watch the Spice.ai local GitHub connector demo](https://img.youtube.com/vi/mxwt0HEF1VQ/hqdefault.jpg)](https://www.youtube.com/embed/mxwt0HEF1VQ)
 
 **Step 0.** Clone the repository if not already cloned.
@@ -24,7 +32,7 @@ cd cookbook/github
 GITHUB_TOKEN=<your_github_token>
 ```
 
-**Setp 2.** Run the Spice runtime with `spice run` from the directory with the `spicepod.yaml` file.
+**Step 2.** Run the Spice runtime with `spice run` from the directory with the `spicepod.yaml` file.
 
 ```bash
 spice run

github/spicepod.yaml

@@ -27,7 +27,7 @@ datasets:
       github_query_mode: search
       github_token: ${secrets:GITHUB_TOKEN}
       github_include_comments: all
-      github_max_comments_fetched: 100
+      github_max_comments_fetched: 75 # 75 is the maximum; higher values are clamped
     time_column: updated_at
     acceleration:
       enabled: true