Add an EXIT STATUS section to the manual page. Currently, nc(1)

does not follow sysexits(3), and returns 1 for all error cases.

PR:		docs/126451

contrib/netcat/nc.1

@@ -445,6 +445,8 @@ The same example again, this time enabling proxy authentication with username
 if the proxy requires it:
 .Pp
 .Dl $ nc -x10.2.3.4:8080 -Xconnect -Pruser host.example.com 42
+.Sh EXIT STATUS
+.Ex -std
 .Sh SEE ALSO
 .Xr cat 1 ,
 .Xr ssh 1 ,