Mkdocs warnings

[Achllle]

mkdocs produces the following warnings that need to be solved:

$ mkdocs serve
INFO     -  Building documentation...
INFO     -  Cleaning site directory
INFO     -  The following pages exist in the docs directory, but are not included in the "nav" configuration:
              - electrical/pcb/control_board/readme.md
              - electrical/pcb/control_board/BOM/v2.0.0/README.md
              - electrical/pcb/control_board/BOM/v2.0.1/README.md
              - electrical/pcb/control_board/documentation/v2.0.1/README.md
              - examples/README.md
              - mechanical/body/laser_cut_parts/README.md
              - parts_list/extra_parts.md
              - parts_list/screws.md
WARNING  -  Documentation file 'README.md' contains a link to 'LICENSE.txt' which is not found in the documentation files.
WARNING  -  Documentation file 'electrical/pcb/README.md' contains a link to 'electrical/pcb/6.1-RoboClaw-Testing-and-Verification' which is not found in the documentation files.
WARNING  -  Documentation file 'mechanical/rocker_bogie/README.md' contains a link to 'integration/README.md' which is not found in the documentation files.
WARNING  -  Documentation file 'mechanical/wheel_assembly/README.md' contains a link to 'mechanical/electrical/wiring/README.md' which is not found in the documentation files.
WARNING  -  Documentation file 'parts_list/README.md' contains a link to 'parts_list/mechanical/body/laser_cut_parts/README.md' which is not found in the documentation files.
WARNING  -  Documentation file 'parts_list/extra_parts.md' contains a link to 'parts_list/mechanical/body/laser_cut_parts/README.md' which is not found in the documentation files.
WARNING  -  Documentation file 'parts_list/screws.md' contains a link to 'parts_list/parts_list/README.md' which is not found in the documentation files.
INFO     -  Documentation built in 0.41 seconds
INFO     -  [11:04:01] Serving on http://127.0.0.1:8000/

See #466