Create a script to keep the sourcecode up-to-date

The update.py script will push changes to a git repo when changes are
found. See the README for more details.

README.md

@@ -8,3 +8,23 @@ Given the main JS file URL, the source code can be downloaded and mapped using:
 ```
 
 For convenience you can run `python update.py`
+
+## Syncing with git repo
+
+The script is designed to keep the contents of a git repo up-to-date with the
+current files. This can be paired with a cronjob to keep an up-to-date version
+of the code someplace.
+
+To ensure the `push` phase of the update works as expected, it is recommended
+to provide an SSH URL for the repository, as we can leverage an SSH key for a
+password-less authentication.
+
+The following example would keep the latest code extracted from dndbeyond.com
+stored in the `ddb_src` directory on the `master` branch of the given git repo.
+If changes are found they are automatically pushed to the repository,
+```
+python update.py \
+ --directory "ddb_src" \
+ --git-repo "ssh://git@git.example.com/test/dndbeyond_src.git"
+ --git-branch "master"
+```