Update issue_board.md to fix one occurrence of the Gitlab edition for multiple issue board feature

doc/user/project/issue_board.md

@@ -34,7 +34,7 @@ and deploy from one single platform. Issue Boards help you to visualize
 and manage the entire process _in_ GitLab.
 
 With [Multiple Issue Boards](#multiple-issue-boards), available
-only in [GitLab Ultimate](https://about.gitlab.com/products/),
+only in [GitLab Enterprise Edition](#features-per-tier),
 you go even further, as you can not only keep yourself and your project
 organized from a broader perspective with one Issue Board per project,
 but also allow your team members to organize their own workflow by creating