Doc: Fix headings in ExampleJax

To properly integrate into our sphinx docs.

python/examples/example_jax/ExampleJax.ipynb

@@ -5,7 +5,10 @@
    "id": "d4d2bc5c",
    "metadata": {},
    "source": [
-    "# Overview\n",
+    "# AMICI & JAX\n",
+    "\n",
+    "## Overview\n",
+    "\n",
     "The purpose of this guide is to showcase how AMICI can be combined with differentiable programming in [JAX](https://jax.readthedocs.io/en/latest/index.html). We will do so by reimplementing the parameter transformations available in AMICI in JAX and comparing it to the native implementation."
    ]
   },
@@ -25,9 +28,9 @@
    "id": "fb2fe897",
    "metadata": {},
    "source": [
-    "# Preparation\n",
+    "## Preparation\n",
     "\n",
-    "To get started we will import a model using the [petab](https://petab.readthedocs.io). To this end, we will use the [benchmark collection](https://github.com/Benchmarking-Initiative/Benchmark-Models-PEtab), which features a variety of different models. For more details about petab import, see the respective notebook petab [notebook](https://amici.readthedocs.io/en/latest/petab.html)."
+    "To get started, we will import a model using the [petab](https://petab.readthedocs.io). To this end, we will use the [benchmark collection](https://github.com/Benchmarking-Initiative/Benchmark-Models-PEtab), which features a variety of different models. For more details about petab import, see the respective notebook petab [notebook](https://amici.readthedocs.io/en/latest/petab.html)."
    ]
   },
   {
@@ -274,7 +277,7 @@
    "id": "e2ef051a",
    "metadata": {},
    "source": [
-    "# JAX implementation\n",
+    "## JAX implementation\n",
     "\n",
     "For full jax support, we would have to implement a new [primitive](https://jax.readthedocs.io/en/latest/notebooks/How_JAX_primitives_work.html), which would require quite a bit of engineering, and in the end wouldn't add much benefit since AMICI can't run on GPUs. Instead, will interface AMICI using the experimental jax module [host_callback](https://jax.readthedocs.io/en/latest/jax.experimental.host_callback.html)."
    ]
@@ -439,7 +442,7 @@
    "id": "293e29fb",
    "metadata": {},
    "source": [
-    "# Testing\n",
+    "## Testing\n",
     "\n",
     "We can now run the function to compute the log-likelihood and the gradient."
    ]
@@ -473,7 +476,7 @@
    "id": "6aa4a5f7",
    "metadata": {},
    "source": [
-    "As a sanity check, we compare the computed value to native parameter transformation in amici. "
+    "As a sanity check, we compare the computed value to native parameter transformation in amici."
    ]
   },
   {