Merge branch 'Add_doc_block_new_users_by_default' into 'master'

Added " How to maintain tight control over the number of active users..."

Added " How to maintain tight control over the number of active users on your GitLab installation" to documentation.

Please check that documentation is OK before accepting Merge. I took if from https://gitlab.com/gitlab-org/gitlab-ce/blob/master/config/gitlab.yml.example#L149

cc/ @sytse

See merge request !1792

doc/raketasks/user_management.md

@@ -47,3 +47,12 @@ sudo gitlab-rake gitlab:import:all_users_to_all_groups
 # installation from source
 bundle exec rake gitlab:import:all_users_to_all_groups RAILS_ENV=production
 ```
+
+## Maintain tight control over the number of active users on your GitLab installation
+
+- Enable this setting to keep new users blocked until they have been cleared by the admin (default: false).
+
+
+```
+block_auto_created_users: false
+```