Fix important typo, from Joachim Henke on netbsd-docs.

Bump date.

external/historical/nawk/bin/awk.1

@@ -1,4 +1,4 @@
-.\"	$NetBSD: awk.1,v 1.3 2014/03/23 01:29:12 dholland Exp $
+.\"	$NetBSD: awk.1,v 1.4 2015/04/06 14:36:41 wiz Exp $
 .\"
 .\" Copyright (C) Lucent Technologies 1997
 .\" All Rights Reserved
@@ -22,7 +22,7 @@
 .\" ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
 .\" THIS SOFTWARE.
 .\"
-.Dd May 25, 2008
+.Dd April 6, 2015
 .Dt AWK 1
 .Os
 .Sh NAME
@@ -485,7 +485,7 @@ for the first occurrence of the regular expression
 in the target string
 .Ar t .
 If
-.Ar s
+.Ar t
 is not given,
 .Va $0
 is used.