Fix #131 by adding link to cheat sheets

Author: stijnvanhoey

_solved/visualization_01_matplotlib.ipynb

@@ -1227,16 +1227,10 @@
     "**Remember**\n",
     "\n",
     "- <a href=\"https://matplotlib.org/stable/gallery/index.html\">matplotlib gallery</a> is an important resource to start from\n",
+    "- Matplotlib has some great [cheat sheets](https://github.com/matplotlib/cheatsheets) available\n",
     "\n",
     "</div>"
    ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": []
   }
  ],
  "metadata": {