Merge branch 'docs-maint-mode-tier' into 'master'

Fix tier badge code

See merge request gitlab-org/gitlab!52963

doc/administration/maintenance_mode/index.md

@@ -4,7 +4,7 @@ group: Geo
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
 ---
-# GitLab in maintenance mode **PREMIUM SELF**
+# GitLab in maintenance mode **(PREMIUM SELF)**
 > [Introduced](https://gitlab.com/groups/gitlab-org/-/epics/2149) in GitLab Premium 13.9.