Add mention of version_slug parameter when using webhook
Fixes
@@ -48,6 +48,14 @@ look something along the lines of ``http://readthedocs.org/build/<project_name>`
Regardless of which revision control system you use, you can just hit this URL
to kick off a rebuild.
+The following parameters available to customize the behavior of custom webhooks:
+
+* ``'version_slug'``: The build version to trigger build for (defaults to ``'latest'``)
+
+ Example::
+
+ $ curl -X POST --data "version_slug=$VERSION" https://readthedocs.org/build/$PROJECT_NAME
+
You could make this part of a hook using Git_, Subversion_, Mercurial_, or
Bazaar_, perhaps through a simple script that accesses the build URL using
``wget`` or ``curl``.
