Regenerate API file, document how it was done

What I need assistance with

This MR uncovered that doc/api/openapi/openapi_v2.yaml and its Rake task bin/rake gitlab:openapi:generate are unowned. I believe it was primarily worked on by Andy Soiron during his time at GitLab. Should the file + task continue to exist, and who should own them?

Changes contained in this MR

As part of the work done in !179858 (merged), I wanted to update doc/api/openapi/openapi_v2.yaml with fixes to a string (cherry pick → cherry-pick).

I wasn't sure how to update the file, so I checked the Git history. I found !152947 (merged), which showed the command bin/rake gitlab:openapi:generate. The Technical Writing team keeps a list of automated pages and their sources (https://docs.gitlab.com/ee/development/documentation/site_architecture/automation.html) - the method of updating the OpenAPI page wasn't listed there, so let's capture that too.

This MR doesn't capture the change to the cherry pick string, because the change to the .rb file containing it hasn't merged yet, but it ensures the next update to this file will be easier.

(@brendan777, FYI - hopefully this process will be clearer for you next time.)

Making it better for the next person.

Related issues

• Related to Inconsistent use of 'cherry-pick' versus 'cherr... (gitlab-docs#1849 - closed)
• Related to OpenAPI page: minor updates, and change YAML fi... (!181582 - merged)
• Related to Document the REST API in OpenAPI V2 (&8926)

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.