docs(reflow): update getting-started — source is public, link to new structure
Missed this in the previous commit (file had been touched mid-write).
- Apply the PR2 factual fix: equalify-reflow is a public AGPL repo,
not 'not yet publicly available'. Pre-release framing is now
four months out of date.
- Link each of the three audience sections to the matching doc in
the new Diátaxis structure (WP plugin how-to + tutorial, API
how-to, reflow-repo README).
- Sentence-case section headings to match the rest of the reorg.
- Drop the 'setup instructions will be available when the plugin
is released' sentence — plugin is released.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>