docs: add note on fork

Co-authored-by: Taylor Turner <taylorfturner@gmail.com>

.github/CONTRIBUTING.md

@@ -109,5 +109,5 @@ If you make changes to the `requirements` text files, please also update the `ad
 
 ## Contributing Documentation Changes and Fixes
 When making adjustments or contributions to documentation, please use the `dev-gh-pages` branch.  This is where all the documentation lives.
-After you've completed your edits, open a Github Pull Request (PR) to merge into `dev-gh-pages`.  During a version release, `dev-gh-pages` is merged
+After you've completed your edits, open a Github Pull Request (PR) to merge into `dev-gh-pages` from your fork.  During a version release, `dev-gh-pages` is merged
 into the `gh-pages` branch and is the version associated with the documentation website and stable version.