doc: use @xref correctly

Silences this warning from new-enough texinfo:
./doc/autoconf.texi:14236: warning: @xref node name should not contain `.'

* doc/autoconf.texi (Macro Definitions): No need for .info.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 1838d6b68f19202ae09672a4d789536028f062eb..029ddd65a15fdf58aa1119e7c1489be7b2f06139 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -14212,7 +14212,7 @@ AC_DEFUN(@var{macro-name}, @var{macro-body})
 @end example
 
 You can refer to any arguments passed to the macro as @samp{$1},
-@samp{$2}, etc.  @xref{Definitions, , How to define new macros, m4.info,
+@samp{$2}, etc.  @xref{Definitions, , How to define new macros, m4,
 GNU M4}, for more complete information on writing M4 macros.
 
 Most macros fall in one of two general categories.  The first category