Broaden CODEOWNERS for data/* YAML files

What does this MR do?

In !174346 (merged), @marcel.amirault cleaned up a lot of problems in data/deprecations/*.yml files. Those files aren't linted (for $reasons) and so lots of spelling and usage issues crept in.

However, he also cleaned up the "What's New" YAML files, which are in data/whats_new/*.yml. Those changes required me to seek engineering approval for !174346 (merged), which I think is overkill. They're just another set of YAML files.

Let's update one line of the CODEOWNERS file (.gitlab/CODEOWNERS) to very slightly broaden what files TWs can review / approve changes to without engineering oversight. I've included the entire section here for context, and marked the change:

## Files that are excluded from required approval
## These rules override the * rule above, so that changes to docs and templates
## can be merged by any user who has maintainer rights, but is not included in
## the * rule (usually technical writers).
/.gitlab/issue_templates/*.md
/.gitlab/merge_request_templates/*.md
/doc/*.md
/doc/**/*.md
/doc/**/*.jpg
/doc/**/*.png
/doc/**/*.svg

## OLD VERSION
/data/deprecations/*.yml

## NEW VERSION
/data/**/*.yml

Related issues

Related to Fix issues in deprecation doc (!174346 - merged)

Author's checklist

• Optional. Consider taking the GitLab Technical Writing Fundamentals course.
• Follow the:
  • Documentation process.
  • Documentation guidelines.
  • Style Guide.
• If you're adding a new page, add the product availability details under the H1 topic title.
• If you are a GitLab team member, request a review based on:
  • The documentation page's metadata.
  • The associated Technical Writer.

If you are a GitLab team member and only adding documentation, do not add any of the following labels:

• ~"frontend"
• ~"backend"
• ~"type::bug"
• ~"database"

These labels cause the MR to be added to code verification QA issues.

Reviewer's checklist

Documentation-related MRs should be reviewed by a Technical Writer for a non-blocking review, based on Documentation Guidelines and the Style Guide.

If you aren't sure which tech writer to ask, use roulette or ask in the #docs Slack channel.

• If the content requires it, ensure the information is reviewed by a subject matter expert.
• Technical writer review items:
  • Ensure docs metadata is present and up-to-date.
  • Ensure the appropriate labels are added to this MR.
  • Ensure a release milestone is set.
  • If relevant to this MR, ensure content topic type principles are in use, including:
    • The headings should be something you'd do a Google search for. Instead of Default behavior, say something like Default behavior when you close an issue.
    • The headings (other than the page title) should be active. Instead of Configuring GDK, say something like Configure GDK.
    • Any task steps should be written as a numbered list.
    • If the content still needs to be edited for topic types, you can create a follow-up issue with the docs-technical-debt label.
• Review by assigned maintainer, who can always request/require the reviews above. Maintainer's review can occur before or after a technical writer review.