document that exit() -> wait() only returns low bits

src/lib/libc/stdlib/exit.3

@@ -33,7 +33,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: exit.3,v 1.4 2000/04/20 13:50:02 aaron Exp $
+.\"	$OpenBSD: exit.3,v 1.5 2001/03/08 20:43:42 deraadt Exp $
 .\"
 .Dd June 29, 1991
 .Dt EXIT 3
@@ -66,6 +66,15 @@ Unlink all files created with the
 .Xr tmpfile 3
 function.
 .El
+Following this,
+.Fn exit
+calls
+.Xr _exit 2.
+Note that typically
+.Xr exit 2
+only passes the lower 8 bits of
+.Fa status
+on to the parent, thus negative values have less meaning.
 .Sh RETURN VALUES
 The
 .Fn exit
@@ -74,6 +83,7 @@ function never returns.
 .Xr _exit 2 ,
 .Xr atexit 3 ,
 .Xr intro 3 ,
+.Xr sysexits 3 ,
 .Xr tmpfile 3
 .Sh STANDARDS
 The