Docs: Add version-specific Duo add-on tier requirements to GraphQL API analytics docs

Problem to solve

The GraphQL API docs for Duo and SDLC Trends state tier requirements as "Premium, Ultimate" for AiUsageData, AiUserMetrics, and AiMetrics. However, on GitLab versions prior to 18.7, these APIs require the Duo Enterprise add-on. A customer on 18.5.x with Duo Pro receives null responses with no error message and no documentation explaining why.

This was fixed in #580174 (merged for 18.7), which removed the Duo Enterprise add-on gating. But customers on supported versions prior to 18.7 have no documentation explaining the requirement.

Source verification: The allowed? method in ee/app/models/ai/duo/enterprise/duo_enterprise_add_on.rb at tag v18.5.4-ee gates access via add_on_for?(:duo_enterprise). This check was removed in the MR for #580174.

Further details

Affected docs:

  • doc/api/graphql/duo_and_sdlc_trends.md — Tier/offering badges and prerequisites

Audience: Self-managed administrators and DevOps leads deploying Duo Pro/Enterprise who use the GraphQL API to measure AI adoption. Particularly affects regulated environments that cannot upgrade immediately.

Related: #548549 (dashboard prerequisites), #580174 (the fix)

Proposal

Add version-specific notes to the GraphQL API docs:

Note: Prior to GitLab 18.7, AiUsageData, AiUserMetrics, and the Duo and SDLC Trends dashboard require the Duo Enterprise add-on. This requirement was removed in GitLab 18.7. If you are on a version prior to 18.7 with Duo Pro, these APIs return null without an error message.