Add Doug Stull as Backend maintainer (Gitlab)

Overview

I have been a Senior Fullstack Engineer at GitLab for 16 months, as a member of groupexpansion, being a trainee maintainer for over a year. In that time I have these stats:

• overall: 523 Merged MRs, 296 reviewed MRs that were merged.
• gitlab-org/gitlab: 178 Merged MRs, 147 reviewed MRs that were merged.
• gitlab-services/version-gitlab-com: 175 Merged MRs, 85 reviewed MRs that were merged.
• gitlab-services/customers-gitlab-com: 42 Merged MRs, 51 reviewed MRs that were merged.
• gitlab-org/license-gitlab-com: 42 Merged MRs, 5 reviewed MRs that were merged.
• Maintainer-On: CustomersDot, Versions App(backend and frontend), LicenseDot, gitlab-styles, gitlab-experiment
• Trainee Maintainer: GitLab(Database)
• gitlab-org/gitlab-styles: 23 Merged MRs with an effort to help MR review cycle time by investing in standardization and automatic linting.

Examples of reviews

• gitlab-org/gitlab!49264 (merged) (community contribution, currently waiting on last DB review)
• gitlab-org/gitlab!48932 (merged) (refactoring suggestions and test performance/provided patch)
• gitlab-org/gitlab!48539 (merged) (public surface area suggestion, DRY thought, test perf, and mixed instance var usage for consistency)
• gitlab-org/gitlab!46357 (merged) (test performance/refactor)
• gitlab-org/gitlab!45382 (merged) (routing/controller suggestions)
• gitlab-org/gitlab!43858 (merged) (general refactoring)

Things to improve

• Domain knowledge.
• Familiarity with graphql/grape, background jobs, caching.
• Wording on feedback to be blameless and help lead to a solution(everyday improvement).
• More focus on testing analysis.

Trainee maintainer issue: #5430 (closed) (lightly maintained as the length of time as a trainee made it hard to keep fresh)

@gitlab-org/maintainers/rails-backend please chime in below with your thoughts, and approve this MR if you agree.

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
  • More than half of the existing maintainers approve the MR
  • 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