Merge branch 'pl-doc-service-desk-email-feature-flag-name' into 'master'

Fix feature flag name for Service Desk

See merge request gitlab-org/gitlab!33385

doc/user/project/service_desk.md

@@ -177,7 +177,7 @@ To turn on the feature, ask a GitLab administrator with Rails console access to
 command:
 
 ```ruby
-Feature.enable(service_desk_email)
+Feature.enable(:service_desk_email)
 ```
 
 The configuration options are the same as for configuring