Improve description of EXIT CODES. Based on the following OpenBSD commit,

forwarded by jmc@openbsd:
----------------------------
revision 1.14
date: 2007/05/20 23:15:57;  author: jmc;  state: Exp;  lines: +19 -18
rewrite DIAGNOSTICS to avoid confusion about which application returns
what, and when;

started by Jeffrey 'jf' Lim, with some correction from Ingo Schwarze;
ok otto
----------------------------

usr.bin/env/env.1

@@ -1,4 +1,4 @@
-.\"	$NetBSD: env.1,v 1.11 2003/08/07 11:13:35 agc Exp $
+.\"	$NetBSD: env.1,v 1.12 2007/06/08 18:20:42 wiz Exp $
 .\"
 .\" Copyright (c) 1980, 1990 The Regents of the University of California.
 .\" All rights reserved.
@@ -30,9 +30,9 @@
 .\" SUCH DAMAGE.
 .\"
 .\"	from: @(#)printenv.1	6.7 (Berkeley) 7/28/91
-.\"	$NetBSD: env.1,v 1.11 2003/08/07 11:13:35 agc Exp $
+.\"	$NetBSD: env.1,v 1.12 2007/06/08 18:20:42 wiz Exp $
 .\"
-.Dd August 27, 1993
+.Dd June 8, 2007
 .Dt ENV 1
 .Os
 .Sh NAME
@@ -75,30 +75,30 @@ of the variables in the environment, with one
 .Ar name=value
 pair per line.
 .Sh EXIT STATUS
-If the
-.Ar utility
-is invoked, the exit status of
 .Nm
-shall be the exit status of
-.Ar utility ;
-otherwise, the
-.Nm
-utility exits with one of the following values:
+exits with one of the following values:
 .Bl -tag -width Ds
 .It 0
-The
+.Ar utility
+was invoked and completed successfully.
+In this case the exit code is returned by the utility itself, not
+.Nm .
+If no utility was specified, then
 .Nm
-utility completed successfully
-.It 1-125
-An error occurred in the
-.Nm
-utility.
+completed successfully and returned the exit code itself.
+.It 1
+An invalid command line option was passed to
+.Nm .
+.It 1\-125
+.Ar utility
+was invoked, but failed in some way;
+see its manual page for more information.
+In this case the exit code is returned by the utility itself, not
+.Nm .
 .It 126
-The utility specified by
 .Ar utility
 was found, but could not be invoked.
 .It 127
-The utility specified by
 .Ar utility
 could not be found.
 .El