Add help text to enforce SSH certificates checkbox

Overview

After

ee/app/views/groups/settings/_enforce_ssh_certificates.html.haml

@@ -2,6 +2,9 @@
   %h5= s_('GroupSettings|Enforce SSH Certificates')
 
   .form-group.gl-mb-3
-    = f.gitlab_ui_checkbox_component :enforce_ssh_certificates,
-        s_('GroupSettings|Enforce SSH Certificates'),
-        checkbox_options: { disabled: !can?(current_user, :admin_group, group), checked: group.enforce_ssh_certificates? }
+    = f.gitlab_ui_checkbox_component :enforce_ssh_certificates, checkbox_options: { disabled: !can?(current_user, :admin_group, group), checked: group.enforce_ssh_certificates? } do |c|
+      - c.with_label do
+        = s_('GroupSettings|Enforce SSH Certificates')
+        = link_to sprite_icon('question-o'), help_page_path('user/group/ssh_certificates')
+      - c.with_help_text do
+        = _('If enabled, individual user accounts will only be able to use issued SSH certificates for Git access. It does not apply to service accounts, deploy keys, and other types of internal accounts.')