Update 'README.md'

README.md

@@ -18,4 +18,5 @@ libchat6 is a complete library that handles an IPv6 only, peer-to-peer, end-to-e
 * The network does not allow store-and-forward of messages if the friend is offline. For mobile clients, notifications might be integrated to wakup the client.
 * The network only allows users to find other users. All end-to-end communication goes directly. (should we allow relay in case the end-to-end doesn't work?)
 * How do chat group work without having to create a full mesh of connections?
+* Should we allow IPv4 only client to relay over a IPv6 client?
 * ... ?