Documentation

Working on the documentation of the code base.
Additional documentation

Added additional documentation for Doxygen
Added source, include, and current directory

Added the source, include, and current directory for which to build the
doxygen documentation.
Improved documentation
Improved Documentation

Improved the documentation for doxygen
Improved RunAction Documentation

Improved the run action documentation
Updated the documentation of HistoManger

Updated the documentation of the HistoManger
Updated EventAction documentation

Updated the EventAction documentation to use doxygen.
Updated documentation of StackingAction

Updated the documentation of stacking action.
Updated SteppingAction documentation

Updated the stepping action documentation of the classes.
Updated documentation of the tracking manager

Updated the documentation of the tracking manager