Add docs/source/rebot_b601.mdx covering single-arm and bimanual
calibration and teleoperation for the reBot B601-DM follower and
reBot Arm 102 leader, with zero-position reference images from the
Seeed Studio wiki. Register the page in the docs toctree.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>