Note that strncmp() will not compare characters after a NUL character.

Add a missing word.  Bump document date.

Inspired by:	IEEE Std 1003.1-200x (Draft 7)
MFC after:	3 days

lib/libc/string/strcmp.3

@@ -36,7 +36,7 @@
 .\"     @(#)strcmp.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd June 4, 1993
+.Dd October 11, 2001
 .Dt STRCMP 3
 .Os
 .Sh NAME
@@ -64,9 +64,16 @@ and
 .Pp
 The
 .Fn strncmp
+function
 compares not more than
 .Fa len
 characters.
+Because
+.Fn strncmp
+is designed for comparing strings rather than binary data,
+characters that appear after a
+.Ql \e0
+character are not compared.
 .Sh RETURN VALUES
 The
 .Fn strcmp