Rename maps to follow the stardard of robot_packages

[jamendezib]

This pull request primarily updates map file references and standardizes file naming for map resources, as well as corrects a robot type name in the documentation. These changes help ensure consistency and accuracy throughout the codebase and documentation.

Map file reference and naming updates:

• Renamed demo_map.yaml to map.yaml and updated its image field from demo_map.png to map.png in common/robotnik_simulation_localization/maps/demo_map/ for consistency.
• Updated the launch file localization_2d.launch.py to reference the new map file name map.yaml instead of demo_map.yaml.
• Renamed electrical_substation_map.yaml to map.yaml and changed its image field from electrical_substation_map.png to map.png in common/robotnik_simulation_localization/maps/electrical_substation_map/.

Documentation update:

• Corrected the robot type name in robotnik_gazebo_ignition/README.md from summit_xl to rbsummit to match the available types.