Use whois.example.com rather than non-existent.host in an example.

usr.bin/whois/whois.1

@@ -256,12 +256,12 @@ The following example demonstrates how to query
 a whois server using a non-standard port, where
 .Dq Li query-data
 is the query to be sent to
-.Dq Li non-existent.host
+.Dq Li whois.example.com
 on port
 .Dq Li rwhois
 (written numerically as 4321).
 .Pp
-.Dl "whois -h non-existent.host -p rwhois query-data"
+.Dl "whois -h whois.example.com -p rwhois query-data"
 .Sh SEE ALSO
 .Rs
 .%A Ken Harrenstien