Clarify that reporters can manage boards

The original issue didn't specify this, but the code always allowed
reporters to do everything here. I think that's correct because

1. Developer permissions normally refer to code, and boards are to do
   with issues.
2. Reporters can manage epics, as well as labels on
   issues, which are in a similar space.

doc/user/project/issue_board.md

@@ -151,7 +151,7 @@ Create lists for each of your team members and quickly drag-and-drop issues onto
 
 ## Permissions
 
-[Developers and up](../permissions.md) can use all the functionality of the
+[Reporters and up](../permissions.md) can use all the functionality of the
 Issue Board, that is, create or delete lists and drag issues from one list to another.
 
 ## GitLab Enterprise features for Issue Boards