Optimize super-linter to validate only Markdown files

[Copilot]

The super-linter job was taking 12m 51s because it ran all linters despite its documented purpose of validating only Markdown files. Other linters (Go, JavaScript, YAML, Shell) already run in separate CI jobs.

Changes

• Configure super-linter environment variables:

  • VALIDATE_MARKDOWN: "true" - Enable Markdown validation
  • VALIDATE_ALL_CODEBASE: "false" - Disable redundant linters

• Update workflow description to reflect actual scope: "Markdown quality checks" instead of "comprehensive code quality checks"

Performance Impact

Expected runtime: ~1-2 minutes (down from 12m 51s)

# Before: all linters run by default
env:
  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
  CREATE_LOG_FILE: "true"

# After: explicit Markdown-only validation
env:
  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
  CREATE_LOG_FILE: "true"
  VALIDATE_MARKDOWN: "true"
  VALIDATE_ALL_CODEBASE: "false"

Original prompt

Reference: https://github.com/githubnext/gh-aw/actions/runs/20523774507/job/58963412871#step:4:1

Review superlinter project helper and update job to make it faster.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.