Update Mitch Nielsen as Charts Maintainer

Trainee maintainer issue:

Maintainer via the proposed scoped changes for the charts project drafted in gitlab-org/charts/gitlab!2737 (merged)

Overview

Has reviewed ~150 charts MRs: https://gitlab.com/gitlab-org/charts/gitlab/-/merge_requests?scope=all&state=merged&approved_by_usernames[]=mnielsen

Examples of reviews

Things to improve

From DJ:

Continue to work towards expanding knowledge of the existing decisions in the codebase and taking more of an architectural role for future decisions.

Developer checklist

• Before this MR is merged
  • Mention @gitlab-org/maintainers/rails-backend, if not done (this issue template should do this automatically)
  • Assign this issue to your manager
• After this MR is merged
  • Request a maintainer from the #backend_maintainers Slack channel to add you as an Owner to gitlab-org/maintainers/rails-backend
  • Consider adding 'backend maintainer' to your Slack notification keywords

Manager checklist

• Before this MR is merged
  • The MR has been open for 5 working days
  • If we have 10 or fewer backend maintainers, more than half of the existing maintainers approve the MR, otherwise if we have 11 or more maintainers, 5 existing maintainers approve the MR (see the maintainer list)
  • There are no blocking concerns raised (if there are, please follow https://about.gitlab.com/handbook/engineering/workflow/code-review/#how-to-become-a-project-maintainer)
• After this MR is merged
  • Announce the good news in the relevant channels listed in https://about.gitlab.com/handbook/engineering/#keeping-yourself-informed