Name/description of the grammar

[Akim Demaille]

It might be silly, but reading the HTML output, it strikes me that we
should give a means to name and describe the parser.  Something that
would allow something better than "GNU Bison XML Automaton Report".
Or at least include the name of the file itself? "GNU Bison XML
Automaton Report for parse-gram.y"?  It could also be used for Doxygen
comments in the generated files.