Update template files for texinfo documentation manuals:
    
        - Stargin using =MANUAL_NAME= translation marker to dynamically
          replace manual's name when new manuals are created.
    
        - Add index inclusion inside manual.texinfo.
    
        - Inside es_ES templates, stop using texinfo special way of print
          special characters. This requires changing the terminal's
          encoding from utf-8 to iso-8859-1 in order for those characters
          to be printed correctly.