docs(notebooks): correct variable assignment in brain surface examples

Author: RicardoRyn

docs/usage/brain_surface.md

@@ -96,7 +96,7 @@ ax1 = plot_brain_surface_figure(plot_data, surf="veryinflated", ax=axes[0,0], ti
 ax2 = plot_brain_surface_figure(plot_data, surf="inflated", ax=axes[0,1], title_name="inflated")
 ax3 = plot_brain_surface_figure(plot_data, surf="midthickness", ax=axes[0, 2], title_name="midthickness")
 ax4 = plot_brain_surface_figure(plot_data, surf="sphere", ax=axes[1,0], title_name="sphere")
-ax4 = plot_brain_surface_figure(plot_data, surf="flat", ax=axes[1,1], title_name="flat")
+ax5 = plot_brain_surface_figure(plot_data, surf="flat", ax=axes[1,1], title_name="flat")
 ```
 
 
@@ -152,7 +152,7 @@ ax2 = plot_brain_surface_figure(plot_data, species="macaque", atlas="charm5", su
 ax3 = plot_brain_surface_figure(plot_data, species="macaque", atlas="charm5", surf="pial", ax=axes[0, 2], title_name="pial")
 ax4 = plot_brain_surface_figure(plot_data, species="macaque", atlas="charm5", surf="midthickness", ax=axes[1,0], title_name="midthickness")
 ax5 = plot_brain_surface_figure(plot_data, species="macaque", atlas="charm5", surf="white", ax=axes[1,1], title_name="white")
-ax5 = plot_brain_surface_figure(plot_data, species="macaque", atlas="charm5", surf="flat", ax=axes[1,2], title_name="flat")
+ax6 = plot_brain_surface_figure(plot_data, species="macaque", atlas="charm5", surf="flat", ax=axes[1,2], title_name="flat")
 ```
 
 

notebooks/brain_surface.ipynb

@@ -146,7 +146,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 10,
+   "execution_count": null,
    "id": "6d8d7e87",
    "metadata": {},
    "outputs": [
@@ -174,7 +174,7 @@
     "ax2 = plot_brain_surface_figure(plot_data, surf=\"inflated\", ax=axes[0,1], title_name=\"inflated\")\n",
     "ax3 = plot_brain_surface_figure(plot_data, surf=\"midthickness\", ax=axes[0, 2], title_name=\"midthickness\")\n",
     "ax4 = plot_brain_surface_figure(plot_data, surf=\"sphere\", ax=axes[1,0], title_name=\"sphere\")\n",
-    "ax4 = plot_brain_surface_figure(plot_data, surf=\"flat\", ax=axes[1,1], title_name=\"flat\")"
+    "ax5 = plot_brain_surface_figure(plot_data, surf=\"flat\", ax=axes[1,1], title_name=\"flat\")"
    ]
   },
   {
@@ -234,7 +234,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 12,
+   "execution_count": null,
    "id": "38c0f8b0",
    "metadata": {},
    "outputs": [
@@ -262,7 +262,7 @@
     "ax3 = plot_brain_surface_figure(plot_data, species=\"macaque\", atlas=\"charm5\", surf=\"pial\", ax=axes[0, 2], title_name=\"pial\")\n",
     "ax4 = plot_brain_surface_figure(plot_data, species=\"macaque\", atlas=\"charm5\", surf=\"midthickness\", ax=axes[1,0], title_name=\"midthickness\")\n",
     "ax5 = plot_brain_surface_figure(plot_data, species=\"macaque\", atlas=\"charm5\", surf=\"white\", ax=axes[1,1], title_name=\"white\")\n",
-    "ax5 = plot_brain_surface_figure(plot_data, species=\"macaque\", atlas=\"charm5\", surf=\"flat\", ax=axes[1,2], title_name=\"flat\")"
+    "ax6 = plot_brain_surface_figure(plot_data, species=\"macaque\", atlas=\"charm5\", surf=\"flat\", ax=axes[1,2], title_name=\"flat\")"
    ]
   },
   {