bbt-wiki

update mapping docs

Add performance optimization note to 'Bathymetric Depth Maps.md' for efficient mapping on low-resource devices

Add detailed import/export guide for waypoints and depth maps. Update 'Bathymetric Depth Maps.md' with links to new content for improved navigation. Enhance 'Waypoints.md' with export-related references.

Add 'Waypoints' guide with detailed instructions on creating, managing, and navigating waypoints. Include table of contents for improved navigation. Update assets with supporting visuals.

Add detailed table of contents to 'Offline Maps.md' and 'The Voice Assistant.md' for better navigation and structure.