Add Info Text to Protected Environments Form

Users will now know that editing this form affects permissions
surrounding feature flags as well.

ee/app/views/projects/protected_environments/_deploy_access_levels_dropdown.html.haml

 .deploy_access_levels-container
-  = dropdown_tag(s_('ProtectedEnvironment|Choose who is allowed to deploy'),
+  = dropdown_tag(s_('ProtectedEnvironment|Choose users'),
     options: { toggle_class: 'js-allowed-to-deploy wide js-multiselect',
     dropdown_class: 'dropdown-menu-user dropdown-menu-selectable',
     filter: true,

ee/app/views/projects/protected_environments/_form.html.haml

@@ -13,6 +13,9 @@
       .form-group
         = f.label :deploy_access_levels_attributes, class: 'label-bold' do
           = s_('ProtectedEnvironment|Allowed to deploy')
+        - if Feature.enabled?(:feature_flag_permissions, @project)
+          .text-muted.mb-2
+            = s_('ProtectedEnvironment|Choose who is allowed to deploy and manage Feature Flag settings')
         = render partial: 'projects/protected_environments/deploy_access_levels_dropdown', locals: { f: f }
 
     .card-footer

ee/changelogs/unreleased/feature-flag-permissions-protected-environments.yml

+---
+title: Alert users that protected environments affects feature flags
+merge_request: 12168
+author:
+type: added

locale/gitlab.pot

@@ -9829,7 +9829,10 @@ msgstr ""
 msgid "ProtectedEnvironment|Allowed to deploy"
 msgstr ""
 
-msgid "ProtectedEnvironment|Choose who is allowed to deploy"
+msgid "ProtectedEnvironment|Choose users"
+msgstr ""
+
+msgid "ProtectedEnvironment|Choose who is allowed to deploy and manage Feature Flag settings"
 msgstr ""
 
 msgid "ProtectedEnvironment|Environment"