docs: add Frames Map 3D wiki Player guide for the 1.21.1 NeoForge line: how to get a map rendered in 3D inside an item frame, the two global client options in config/maps3d-client.properties, the per-map settings stored on the map item, compatibility (Iris, client-optional multiplayer, dedicated servers) and the fork attribution and authorisation. Co-Authored-By: Claude <noreply@anthropic.com>