Fix description of AC_CONFIG_TESTDIR to not mention atconfig.in.

[Ralf Wildenhues]

OK?  This got me confused at first.

Also, should we document any of $at_srcdir, $at_top_srcdir etc?
I would like to know from within the testsuite if we're in a VPATH
build or not.  I guess same question (whether to document or not)
holds for $ac_srcdir, $ac_top_srcdir etc. inside configure.

Thanks,
Ralf

    Fix description of AC_CONFIG_TESTDIR to not mention atconfig.in.
    
    * doc/autoconf.texi (Making testsuite Scripts): atconfig is not
    created from an input template.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 69564c4..0f64115 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -24244,9 +24244,9 @@ Invoke @code{AC_CONFIG_TESTDIR}.
 @defmac AC_CONFIG_TESTDIR (@var{directory}, @dvar{test-path, directory})
 @acindex{CONFIG_TESTDIR}
 An Autotest test suite is to be configured in @var{directory}.  This
-macro requires the instantiation of @address@hidden/atconfig} from
address@hidden@var{directory}/atconfig.in}, and sets the default
address@hidden to @var{test-path} (@pxref{testsuite Invocation}).
+macro causes @address@hidden/atconfig} to be created by
address@hidden and sets the default @code{AUTOTEST_PATH} to
address@hidden (@pxref{testsuite Invocation}).
 @end defmac
 
 @item