Merge branch 'docs-subgroup-issues-in-group-board' into 'master'

Update docs subgroup issues in group board

See merge request gitlab-org/gitlab-ee!5398

doc/user/project/issue_board.md

@@ -307,10 +307,8 @@ If you don't have editing permission in a board, you're still able to see the co
 
 > Introduced in [GitLab Enterprise Edition 10.0 Premium](https://about.gitlab.com/2017/09/22/gitlab-10-0-released/#group-issue-boards).
 
-Group issue boards are analogous to project-level issue boards and they are accessible at the group
-navigation level. A group-level issue board allows you to view all issues from all projects in that group
-(currently, it does not see issues from projects in subgroups). You can only associate group milestones
-and filter by group milestones for these boards. Similarly, you can only filter by group labels for these
+Group issue board is analogous to project-level issue board and it is accessible at the group
+navigation level. A group-level issue board allows you to view all issues from all projects in that group or descendant subgroups. Similarly, you can only filter by group labels for these
 boards. When updating milestones and labels for an issue through the sidebar update mechanism, again only
 group-level objects are available.