Add cross references between the 2 whois scripts

scripts/whois-domain.nse

@@ -3,6 +3,8 @@ Attempts to retrieve information about the domain name of the target
 ]]
 
 ---
+-- @see whois-ip.nse
+--
 -- @usage nmap --script whois-domain.nse <target>
 --
 -- This script starts by querying the whois.iana.org (which is the root of the

scripts/whois-ip.nse

@@ -42,6 +42,7 @@ the RIRs.
 ]]
 
 ---
+-- @see whois-domain.nse
 -- @args whodb Takes any of the following values, which may be combined:
 -- * <code>whodb=nofile</code> Prevent the use of IANA assignments data and instead query the default services.
 -- * <code>whodb=nofollow</code> Ignore referrals and instead display the first record obtained.