invoke.texi: Use @table @samp instead of @itemize @minus for table of language standards.

invoke.texi: Use @table @samp instead of @itemize @minus for table of language standards.

	* invoke.texi: Use @table @samp instead of @itemize @minus for
	table of language standards.  Fix use of @pxref.  From Zack
	Weinberg.  Also exclude specs documentation from generated
	manpage, and create separate ENVIRONMENT section.

From-SVN: r38069