Update user doc to include the recent added imported fields

Related to:
- https://gitlab.com/gitlab-org/gitlab/-/issues/321675
- Group Members: https://gitlab.com/gitlab-org/gitlab/-/issues/299415
- Group Labels: https://gitlab.com/gitlab-org/gitlab/-/issues/292429
- Epic Labels: https://gitlab.com/gitlab-org/gitlab/-/issues/297460
- Epic parent: https://gitlab.com/gitlab-org/gitlab/-/issues/297459
- Epic author: https://gitlab.com/gitlab-org/gitlab/-/issues/298745
- Epic emoji award: https://gitlab.com/gitlab-org/gitlab/-/issues/297466

doc/user/group/import/index.md

@@ -20,11 +20,18 @@ Using GitLab Group Migration, you can migrate existing top-level groups from Git
 
 The following resources are migrated to the target instance:
 
-- Groups
+- Groups ([Introduced in 13.7](https://gitlab.com/groups/gitlab-org/-/epics/4374))
   - description
   - attributes
   - subgroups
-- Epics
+- Labels ([Introduced in 13.9](https://gitlab.com/gitlab-org/gitlab/-/issues/292429))
+- Members ([Introduced in 13.9](https://gitlab.com/gitlab-org/gitlab/-/issues/299415))
+  Group members are associated with the imported group if:
+  - The user already exists in the target GitLab instance and
+  - The user has a public email in the source GitLab instance that matches a
+    confirmed email in the target GitLab instance
+    confirmed email in the target GitLab instance
+- Epics ([Introduced in 13.7](https://gitlab.com/gitlab-org/gitlab/-/issues/250281))
   - title
   - description
   - state (open / closed)
@@ -32,6 +39,10 @@ The following resources are migrated to the target instance:
   - due date
   - epic order on boards
   - confidentiality
+  - labels ([Introduced in 13.9](https://gitlab.com/gitlab-org/gitlab/-/issues/297460))
+  - author ([Introduced in 13.9](https://gitlab.com/gitlab-org/gitlab/-/issues/298745))
+  - parent epic ([Introduced in 13.9](https://gitlab.com/gitlab-org/gitlab/-/issues/297459))
+  - emoji award ([Introduced in 13.9](https://gitlab.com/gitlab-org/gitlab/-/issues/297466))
 
 Any other items are **not** migrated.