Update `help.sh':
    
        - Fix regular expression describing what locations can be used as
          source location for writing documentation manuals. Only
          `trunk/Manuals' and `branches/Manuals/BRANCHNAME' are permitted
          to be used as source locations for writing documentation
          manuals.
    
          When none of these locations is the current working directory
          (e.g., determined through PWD variable), then the
          `trunk/Manuals' location is used as default value for writing
          documentation manuals.