add docs for gitreload

doc/development.md

@@ -72,3 +72,25 @@ Very handy: if you uncomment the `--pdb` argument in `NOSE_ARGS` in `lms/envs/te
 If you change course content, while running the LMS in dev mode, it is unnecessary to restart to refresh the modulestore.  
 
 Instead, hit /migrate/modules to see a list of all modules loaded, and click on links (eg /migrate/reload/edx4edx) to reload a course.
+
+### Gitreload-based workflow
+
+github (or other equivalent git-based repository systems) used for
+course content can be setup to trigger an automatic reload when changes are pushed.  Here is how:
+
+1. Each content directory in mitx_all/data should be a clone of a git repo
+
+2. The user running the mitx gunicorn process should have its ssh key registered with the git repo
+
+3. The list settings.ALLOWED_GITRELOAD_IPS should contain the IP address of the git repo originating the gitreload request.
+    By default, this list is ['207.97.227.253', '50.57.128.197', '108.171.174.178'] (the github IPs).
+    The list can be overridden in the startup file used, eg lms/envs/dev*.py
+
+4. The git post-receive-hook should POST to /gitreload with a JSON payload.  This payload should define at least
+
+   { "repository" : { "name" : reload_dir }
+
+    where reload_dir is the directory name of the content to reload (ie mitx_all/data/reload_dir should exist)
+
+    The mitx server will then do "git reset --hard HEAD; git clean -f -d; git pull origin" in that directory.  After the pull,
+    it will reload the modulestore for that course.