chore: drop MAINTAINER_ACTIONS.md from the PR

Maintainer manages these org-gated actions directly. The analytics provisioning
steps (GoatCounter, STATS_GITHUB_TOKEN PAT) remain documented in
website/docs/architecture/external-analytics.md.

Claude-Session: https://claude.ai/code/session_01XFiuAUxNS9riUJFFBEHvui

Author: Shutong Wu