Merge branch 'isandin-master-patch-84354' into 'master'

Add link to SM bulk assignment rake task documentation

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/144779



Merged-by: Suzanne Selhorn <sselhorn@gitlab.com>
Co-authored-by: Isabel Sandin <isandin@gitlab.com>

doc/subscriptions/subscription-add-ons.md

@@ -56,3 +56,5 @@ Prerequisites:
 To assign seats in bulk, you can use [this GraphQL API endpoint](../api/graphql/reference/index.md#mutationuseraddonassignmentcreate).
 
 This endpoint works for both self-managed and SaaS.
+
+Administrators of self-managed instances can also assign users by using a [Rake task](../raketasks/user_management.md#bulk-assign-users-to-gitlab-duo-pro).