Add customizable buttons for NEWS/RELEASE-NOTES to the fast-access bar in project view pane
Description
GitLab already adds fast-access buttons to the project view, which allows an user to read interesting information like ChangeLog, LICENSE, CONTRIBUTING[.md].
However, some projects have rather dense ChangeLogs (e.g. generated from the git commit logs), and thus publish a high-level "more relevant changes" version of the ChangeLog or other release notes either in the NEWS file, or in a RELEASE-NOTES or UPGRADING file. For those projects, the choice of the ChangeLog file for fast-access is not optimal.
~"feature proposal"
Proposal
Allow a project to select which such files to display. E.g. for the iucode-tool/iucode-tool project, I'd rather display the NEWS file than the ChangeLog file. Other projects might want to display both NEWS and RELEASE-NOTES, or NEWS and ChangeLog, etc.
I suggest that it should be possible for a project to customize a small set of top-level buttons to show (NEWS, ChangeLog, RELEASE-NOTES, etc).
A flexible way to implement this feature would be to allow, say, up to three per-project customizable buttons, and allow the project to configure the button label (maybe from a drop-list, if free-text is not desired), and the file each button should map to.
If this feature replaces the current set of "hardwired" buttons, a project would need more customizable button slots than three. I'd suggest eight to ten button slots in that case.