Add docs on multiple issue boards

[ci skip]

doc/user/project/issue_board.md

@@ -154,6 +154,21 @@ to another list the label changes and a system not is recorded.
 
 ![Issue Board system notes](img/issue_board_system_notes.png)
 
+## Multiple issue boards
+
+> Introduced in [GitLab Enterprise Edition][ee] 8.13.
+
+Multiple issue boards, as the name suggests, allow for more than one issue board
+for a given project. This is great for large projects with more than one team
+or in situations where a repository is used to host the code of multiple
+products.
+
+Clicking on the current board name in the upper left corner will reveal a
+menu from where you can create another issue board and rename or delete the
+existing one.
+
+![Multiple issue boards](img/issue_boards_multiple.png)
+
 ## Permissions
 
 [Developers and up](../permissions.md) can use all the functionality of the
@@ -179,6 +194,7 @@ A few things to remember:
   20 will appear.
 
 [ce-5554]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5554
+[ee]: https://about.gitlab.com/gitlab-ee/
 [labels]: ./labels.md
 [scrum]: https://en.wikipedia.org/wiki/Scrum_(software_development)
 [kanban]: https://en.wikipedia.org/wiki/Kanban_(development)