PROS 4: Improve Header Documentation for Doxygen Integration

[WillXuCodes]

Expected Behavior:

Currently, our documentation attempts to follow the doxygen release structure as much as possible, but there are some areas where this can be improved. Furthermore, we still need to add examples to the header files.

https://github.com/purduesigbots/pros/blob/664be01244b983f266501f785a99f4de2ff9b1c3/include/pros/motors.hpp

A good example of this can be found in the file above, which is is connected to our doxygen proof of concept that can be found here:

https://purduesigbots.github.io/pros-doxygen-docs/group__cpp-motors.html