Add docs for new gitlab-exporter server_name setting (!51322) · Merge requests · GitLab.org / GitLab · GitLab

What does this MR do?

This adds documentation for a new gitlab-exporter setting introduced in omnibus-gitlab!4896 (merged)

Does this MR meet the acceptance criteria?

Conformity

[-] Changelog entry
Documentation (if required)
Code review guidelines
[-] Merge request performance guidelines
Style guides
[-] Database guides
[-] Separation of EE specific content

Related to #293687 (closed)