[MattieGit]

Summary

• Link the Home Assistant core integration (hr_energy_qube) in the intro and under Related Projects, next to the HACS integration.
• Fix the usage example: read_state() and disconnect() don't exist; use get_all_data() (which can return None) and close().
• List missing features: reconnect with backoff, batched reads, validated writes, SG Ready, unified status, py.typed / mypy --strict.
• Note the Python 3.12+ requirement.

Docs only; no version bump. PyPI shows the new README from the next release.