Merge branch 'explain-setting' into 'master'

Explain setting

doc/public_access/public_access.md

@@ -26,3 +26,7 @@ The public page of users, located at `/u/username` is visible if either:
 Otherwise, you will be redirected to the sign in page.
 
 When visiting the public page of an user, you will only see listed projects which you can view yourself.
+
+#### Restricting the use of public or internal projects
+In [gitlab.yml](https://gitlab.com/gitlab-org/gitlab-ce/blob/dbd88d453b8e6c78a423fa7e692004b1db6ea069/config/gitlab.yml.example#L64) you can disable public projects or public and internal projects for the entire GitLab installation to prevent people making code public by accident.
+