Update the UPDATING THE DOCS doc

Signed-off-by: Michael Gielda <mgielda@antmicro.com>

UPDATING-THE-DOCS.md

@@ -1,8 +1,9 @@
 # Guide to updating the Project X-Ray docs
 
 We welcome updates to the Project X-Ray docs. The docs are published on [Read
-the Docs](http://prjxray.readthedocs.io) and the source is on
-[GitHub](https://github.com/SymbiFlow/prjxray/tree/master/docs).
+the Docs](http://prjxray.readthedocs.io) and the source is on the [docs branch on GitHub](https://github.com/SymbiFlow/prjxray/tree/docs/docs).
+
+The reason for using the `docs` branch is to avoid running the full CI test suite which triggers when merging anything to `master`. Ultimately of course the `docs` branch needs to be synchronized with `master`, but this can be done in bulk.
 
 Updating the docs is a three-step process: Make your updates, test your updates,
 send a pull request.
@@ -110,7 +111,7 @@ Follow these steps to create your own staging doc site on Read the Docs (RtD):
    Reason for protecting your doc site: If you leave your doc site public, it
    will appear in web searches. That may be confusing for readers who are
    looking for the canonical Project X-Ray docs.
-1. Set RtD to build from your branch, rather than from master. This ensures
+1. Set RtD to build from your branch, rather than from `docs`. This ensures
    that the content you see on your doc site reflect your latest updates:
    -  On [your RtD dashboard](https://readthedocs.org/dashboard/),
       open **your project**, then go to **Admin > Advanced Settings.**