Merge pull request #5587 from drevicko/patch-1

Update git-hooks/README.md

git-hooks/README.md

@@ -6,4 +6,5 @@ For now, we just have `post-checkout` and `post-merge`,
 both of which just update submodules,
 so make sure that you have a fully synced repo whenever you checkout or pull.
 
-To use these hooks, run `./install-hooks.sh`.
+To use these hooks, run `./install-hooks.sh`. 
+If you havn't initialised and updated the submodules manually, you will then need to run `git checkout master` to activate the hooks (even if you already have `master` checked out).