Follow-up from "Add option to delete cached Kubernetes namespaces"

The following discussion from !20411 (merged) should be addressed:

• @eread started a discussion: (+4 comments)

  To clear the cache:
  
  1. Navigate to the cluster settings page.
  1. Expand the **Advanced settings** section.
  1. Click **Clear cluster cache**.

  Is this available for group, projects, and instance clusters? We should be more specific. Here's a pattern: https://docs.gitlab.com/ee/user/clusters/management_project.html#selecting-a-cluster-management-project (see the "if group level, then... if project level, then....").

  The docs here imply "project" only, so at the very least step 1 is the navigation to the project cluster page.