fix: inconsistencies which code cells are editable

If a section has an code example and encourages the
reader to experiment around, the code cell with the
initial example should be editable

src/01_grundlagen.ipynb

@@ -372,7 +372,7 @@
    "execution_count": null,
    "id": "5feeda4a-682f-419e-bda4-b8c85c7e9d5e",
    "metadata": {
-    "editable": false,
+    "editable": true,
     "slideshow": {
      "slide_type": ""
     },
@@ -400,7 +400,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "69014430-eb93-4f42-b12d-d4a3c3135043",
+   "id": "6ba975a5-1a7a-44e9-be8f-3483ec595ec0",
    "metadata": {
     "editable": true,
     "slideshow": {
@@ -410,14 +410,6 @@
    },
    "outputs": [],
    "source": []
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "id": "6ba975a5-1a7a-44e9-be8f-3483ec595ec0",
-   "metadata": {},
-   "outputs": [],
-   "source": []
   }
  ],
  "metadata": {