add a note and fix histogram code

Author: Corvince

docs/tutorials/visualization_tutorial.ipynb

@@ -194,7 +194,9 @@
     "\n",
     "If the visualization elements provided by Mesa aren't enough for you, you can build your own and plug them into the model server.\n",
     "\n",
-    "For this example, let's build a simple histogram visualization, which can count the number of agents with each value of wealth."
+    "For this example, let's build a simple histogram visualization, which can count the number of agents with each value of wealth.\n",
+    "\n",
+    "**Note:** Due to the way solara works we need to trigger an update whenever the underlying model changes. For this you need to register an update counter with every component."
    ]
   },
   {
@@ -205,9 +207,11 @@
    "source": [
     "import solara\n",
     "from matplotlib.figure import Figure\n",
+    "from mesa.visualization.utils import update_counter\n",
     "\n",
     "@solara.component\n",
     "def Histogram(model):\n",
+    "    update_counter.get() # This is required to update the counter\n",
     "    # Note: you must initialize a figure using this method instead of\n",
     "    # plt.figure(), for thread safety purpose\n",
     "    fig = Figure()\n",