Update help functionality and tcar-fs documentation models.
    
    Previous to this commit, the help functionality doesn't produce
    Tcar-fs documentation manual in Texinfo format correctly because of
    the document structure modifications (i.e., it was removed all the
    Trunk, Branches and Tags chapters as well as all the related
    references to them from source files) and the location used as based
    to produce the documentation.
    
    In this commit, I make the help functionality to produce Tcar-fs
    documentation manual by changing the production base location from
    repository's first directory level to documentation model's first
    directory level. Additionally, the following changes were also
    committed:
    
     - Fix some references inside Tcar-fs documentation models themselves
       in order for the manual to build correctly.
    
     - Centralize licenses information. Don't duplicate the Licenses
       chapter from its default template directory.  Instead, create a
       symbolic link to it.