Add Evan Read as docs maintainer for Gitaly project

Why is this change being made?

I'm a maintainer on the gitaly project, but this isn't reflected on the Engineering Projects page: https://about.gitlab.com/handbook/engineering/projects/#gitaly or in Reviewer Roulette for gitaly project.

This sets me to be Docs Maintainer, for logic that requires it.

CC @dianalogan @kpaizee

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
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  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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