Add repository variable CI_RUN_ON_MAIN that gates whether pushes to
main trigger CI. When unset (default), pushes to main skip CI;
set to 'true' to enable. Pushes to other branches are unaffected.
Reorganize GitHub Actions docs into a dedicated tools/github/actions/
directory and consolidate every CI repository variable in a single
SPOT (configuration.md). Move actions.md to actions/workflows.md and
branch/configuration.md to actions/configuration.md, then update
every cross-reference. Trim README files to scope-only per
docs/contributing/artefact/files/docs/readme_md.md.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
- document docs README purpose and scope in a dedicated SPOT
- add scope-focused README.md files across docs directories
- remove lint rule that banned README.md files under docs