* doc/gcc.texi (G++ and GCC): Mention Ada front end.
	(Standards): Refer to GNAT Reference Manual.

	* doc/install.texi (Configuration): Mention Ada front end.
	(Building): Add build instructions for the Ada front end.

	* doc/invoke.texi (Overall Options): Document Ada file types.
	Add "ada" to "-x LANGUAGE" option parameters.

From-SVN: r46479