Docs: note removal of app label support

doc/user/project/deploy_boards.md

@@ -86,8 +86,7 @@ To display the Deploy Boards for a specific [environment] you should:
    Kubernetes.
 
    NOTE: **Note:**
-   The Kubernetes label of `app` is deprecated and may be removed in next major
-   release, GitLab 12.0.
+   Matching based on the Kubernetes `app` label was removed in [GitLab 12.1](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14020)
 
     ![Deploy Boards Kubernetes Label](img/deploy_boards_kubernetes_label.png)