submap_service inconsistency between docs and param file

[sarahnator]

Thanks for this package, I just wanted to give a headsup about the submap_service parameter value:

• robot.yaml: submap_service: "/elevation_mapping_long_range/get_submap"
• parameter documentation: submap_service (string, default: "/elevation_mapping/get_grid_map")

Changing the robot.yaml value to match might help save others some time and confusion.