Merge branch '6892-fix-board-update-doc' into 'master'

Update doc to note that board update API is available after 11.1.

Closes #6892

See merge request gitlab-org/gitlab-ee!6496

doc/api/boards.md

@@ -211,6 +211,8 @@ Example response:
 
 ## Update a board **[STARTER]**
 
+> [Introduced][ee-5954] in GitLab 11.1.
+
 Updates a board.
 
 ```
@@ -472,3 +474,5 @@ DELETE /projects/:id/boards/:board_id/lists/:list_id
 ```bash
 curl --request DELETE --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/projects/5/boards/1/lists/1
 ```
+
+[ee-5954]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5954

doc/api/group_boards.md

@@ -275,6 +275,8 @@ Example response:
 
 ## Update a board
 
+> [Introduced][ee-5954] in GitLab 11.1.
+
 Updates a board.
 
 ```
@@ -548,3 +550,5 @@ DELETE /groups/:id/boards/:board_id/lists/:list_id
 ```bash
 curl --request DELETE --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/groups/5/boards/1/lists/1
 ```
+
+[ee-5954]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5954