Docs feedback: Global custom hook instructions don't work

https://docs.gitlab.com/12.4/ee/administration/custom_hooks.html

On a new Omnibus installation of GitLab CE, I have created the following file:

/opt/gitlab/embedded/service/gitlab-shell/hooks/custom_hooks/pre-receive.d/pre-receive

And set the following in gitlab.rb (just to make sure, I think that's a default value):

gitlab_shell['custom_hooks_dir'] = "/opt/gitlab/embedded/service/gitlab-shell/hooks"

The pre-receive hook is not getting executed when I expect it to be. When I make a commit, it's not rejecting the commit.