doc: splitted the module documentation file

The module documentation file is now modular itself. Each module has its
own file in the Documentation/ directory.

Also, fixed some generic documentation errors across the project.

Signed-off-by: Michel Megens <dev@michelmegens.net>
doxygen: added the module files to the Doxyfile

Added the files describing and documenting each module to the Doxygen
configuration file (Doxyfile).

Signed-off-by: Michel Megens <dev@michelmegens.net>
ETA/OS 0.2.0

Signed-off-by: Michel Megens <dev@michelmegens.net>