fix: add links

Author: jonas-eschle

Custom_PDF.ipynb

@@ -202,9 +202,10 @@
     "\n",
     "So far, we used rather simple examples and many basic shapes, such as polynomials, already have an efficient implementation within zfit. Therefore, we will now create a three dimensional PDF measuring the angular observables of a $B^+ \\rightarrow K^* l l$ decay.\n",
     "\n",
-    "The implementation is not \"special\" or complicated at all, it rather shows how to deal with multiple dimensions and how to manage several parameters. It was created using the equation of the angular observables (taken from a paper).\n",
+    "The implementation is not \"special\" or complicated at all, it rather shows how to deal with multiple dimensions and how to manage several parameters. It was created using the equation of the angular observables (taken from the paper).\n",
     "\n",
-    "_Many thanks to Rafael Silva Coutinho for the implementation!_"
+    "[**Using ComPWA to build amplitudes (and zfit to fit them)**](https://compwa-org.readthedocs.io/report/020.html)\n",
+    "\n"
    ]
   },
   {

Simultaneous_fit_discovery_splot.ipynb

@@ -173,18 +173,21 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "outputs": [],
-   "source": [
-    "result = minimizer.minimize(nll)\n",
-    "result.hesse();"
-   ],
    "metadata": {
-    "collapsed": false,
     "ExecuteTime": {
      "end_time": "2023-10-08T18:11:30.168222657Z",
      "start_time": "2023-10-08T18:11:28.564116262Z"
+    },
+    "collapsed": false,
+    "jupyter": {
+     "outputs_hidden": false
     }
-   }
+   },
+   "outputs": [],
+   "source": [
+    "result = minimizer.minimize(nll)\n",
+    "result.hesse();"
+   ]
   },
   {
    "cell_type": "code",
@@ -901,11 +904,11 @@
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
-    "scrolled": true,
     "ExecuteTime": {
      "end_time": "2023-10-08T18:23:15.974037308Z",
      "start_time": "2023-10-08T18:23:15.701744201Z"
-    }
+    },
+    "scrolled": true
    },
    "outputs": [],
    "source": [
@@ -1034,7 +1037,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.4"
+   "version": "3.11.5"
   }
  },
  "nbformat": 4,