Clarified who can set labels based on community contributor experience

doc/development/contributing/issue_workflow.md

@@ -36,7 +36,7 @@ project.
 
 To allow for asynchronous issue handling, we use [milestones](https://gitlab.com/groups/gitlab-org/-/milestones)
 and [labels](https://gitlab.com/gitlab-org/gitlab/-/labels). Leads and product managers handle most of the
-scheduling into milestones. Labeling is a task for everyone.
+scheduling into milestones. Labeling is a task for everyone. (For some projects, labels can be set only by GitLab team members and not by community contributors).
 
 Most issues will have labels for at least one of the following: