Add Merge Request Commits keyboard shortcuts c and x to shortcuts help page
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=292053)
</details>
<!--IssueSummary end-->
Add Merge Request Commits keyboard shortcuts c and x to https://docs.gitlab.com/ee/user/shortcuts.html
I ended up on that page when searching for shortcuts to next and previous commit and didn't find what I was looking for.
I think in general you need a process for updating the shortcuts.html page when you are adding shortcuts so people can know about them.
Adding a tooltip to the buttons showing the shortcut, would be even better.
issue