docs: Rome-context line atop the upstream README

[anil-rome]

Fleet-audit fix: this fork's README was pure upstream with zero Rome context. Adds one line at the top saying what the fork is for in Rome's stack + links to the org and docs. No other changes.

[anil-rome]

Note for the record: the red Dispatch rome-rollup-clients image build check is the push-triggered cross-repo dispatch failing on token permissions (Resource not accessible by integration) — it fires on any branch push, fails before any build, and is unaffected by this README-only diff. The PR's own checks are green.