Add docstring documentation for all arguments

[brylie]

Currently, the track function docstring only describes the total parameter:

track(iterable=None, total=0, keep=True, cycle=False, label=None)
Docstring:     
Progressbar supports displaying a progressbar like element 
    
Init docstring:
Creates a new progressbar

Parameters
----------
total : int
    maximum size of the progressbar

Please consider adding a brief description of the remaining parameters to the docstring. This helps developers to understand how to use the library.