docs: §3b for GitHub + Odoo.sh projects, refresh the stale RWI example

Adds a section for the GitHub-hosted half of the fleet, and corrects an example that had gone false.

§3b — GitHub + Odoo.sh projects

None of §3 applies to these. Odoo.sh runs tests only on dev-stage branches and reports nothing back to GitHub — no commit statuses, no check runs — so a branch ruleset has nothing to require, and gh pr merge --auto merges as soon as a PR is mergeable. In practice PRs were merging with no test having run.

The section covers what contributors now see (a required tests check), why a build can fail with "browser test skipped" and why that must not be worked around, and where to debug a misbehaving runner.

Full architecture lives in bemade/odoo-ci → docs/github-actions-runner.md; this only carries what a contributor needs.

§9 — the RWI example was wrong in every field

It still described GitLab + Bemade Kubernetes: git.bemade.org:rwi/odoo, branch 19.0, namespace rwi, rwi.odoo.bemade.org, submodules. RWI is on GitHub + Odoo.sh with vendored addons. Replaced with the real configuration and a note that the old repo is archived.

Also genericized the other illustrative rwi/ paths (§1, §5) to acme/ so they stop asserting something untrue, and scoped §3's Deploy stage to GitLab-hosted projects.