Doc: show plotting measurements

It seems, the documentation didn't demonstrate how to plot measurements together with the model outputs yet.

python/examples/example_steadystate/ExampleSteadystate.ipynb

@@ -985,6 +985,20 @@
     "print(\"Log-likelihood %f\" % rdata[\"llh\"])"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": "The provided measurements can be visualized together with the simulation results by passing the `Expdata` to `amici.plotting.plot_observable_trajectories`:"
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "amici.plotting.plot_observable_trajectories(rdata, edata=edata)"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},