Change header from '##' to '#' in notebooks.ipynb

Author: Tom-van-Woudenberg

book/version_control/notebooks.ipynb

@@ -5,7 +5,7 @@
    "id": "962e8194",
    "metadata": {},
    "source": [
-    "## Jupyter notebooks and git\n",
+    "# Jupyter notebooks and git\n",
     "\n",
     "Version control systems oriented towards software development and programming are typically focused on **text-based files**: files where the contents are viewable on your computer as human-readable text. **Binary files,** on the other hand, are organized and saved with bits (`0`'s and `1`'s) and are not human-readable. Although this may be a simplified description in terms of the way computers store information (you can read more [here](https://en.wikipedia.org/wiki/Binary_file)), it is enough for our purposes to recognize that text-based files are best suited for use with version control system; in other words, your Python code!\n",
     "\n",