Update Merge request diffs storage page based on initial review
## Issue description
This page describes product documentation work that was identified during a [documentation review](https://gitlab.com/gitlab-org/technical-writing/-/issues/403) of documentation pages associated with the Create:Editor stage/group.
Page: https://docs.gitlab.com/ee/administration/merge_request_diffs.html
## Identified items
* This page feels marooned. I suspect grepping for `merge request diff` will turn up some places we should cross-link it.
* Move `... if your terminal does not support ANSI escape codes` to the `ANSI` variable it references.
issue