clarifications from ray lai;

tweaked by tedu@ and myself;

src/lib/libc/stdlib/strtonum.3

@@ -1,4 +1,4 @@
-.\" $OpenBSD: strtonum.3,v 1.11 2005/04/14 07:58:46 jmc Exp $
+.\" $OpenBSD: strtonum.3,v 1.12 2005/10/26 11:37:58 jmc Exp $
 .\"
 .\" Copyright (c) 2004 Ted Unangst
 .\"
@@ -77,7 +77,9 @@ The
 .Fn strtonum
 function returns the result of the conversion,
 unless the value would exceed the provided bounds or is invalid.
-On error, 0 is returned and
+On error, 0 is returned,
+.Va errno
+is set, and
 .Fa errstr
 will point to an error message.
 .Fa *errstr
@@ -100,7 +102,7 @@ if (errstr)
 .Ed
 .Pp
 The above example will guarantee that the value of iterations is between
-1 and 64.
+1 and 64 (inclusive).
 .Sh ERRORS
 .Bl -tag -width Er
 .It Bq Er ERANGE