remove broken links

Author: j-atkins

docs/user-guide/assignments/Research_proposal_intro.ipynb

@@ -150,9 +150,15 @@
     "\n",
     "Finally, fit your equipment in the 20-foot container. The container will be sent to your port of departure ahead of time with a cargo boat, so make sure you are packed in time for this transfer. Remember there are no shops at sea, so think carefully and plan ahead. \n",
     "\n",
-    "![Equipment preparation NIOZ](https://www.nioz.nl/application/files/9116/7500/3457/2023-01-16-packing.jpg) \n",
-    "![Equipment loading](https://www.nioz.nl/application/files/7416/7810/2265/2023-03-06-container-shifting.jpg) "
+    "<!-- TODO: these images are no longer hosted -->\n",
+    "<!-- ![Equipment preparation NIOZ](https://www.nioz.nl/application/files/9116/7500/3457/2023-01-16-packing.jpg) \n",
+    "![Equipment loading](https://www.nioz.nl/application/files/7416/7810/2265/2023-03-06-container-shifting.jpg)  -->"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": []
   }
  ],
  "metadata": {