include some basic I2CP info

core/java/src/net/i2p/client/package.html

@@ -29,4 +29,15 @@ but there are three other subpackages that are helpful.  Specifically:<ul>
     the streaming library is packaged seperate from the main SDK - in the 
     ministreaming.jar)</li>
 </ul></p>
+
+<p>The {@link net.i2p.client.I2PSession} implementation itself communicates with
+the I2P router by the I2CP (the client protocol).  This is done over a 
+bidirectional TCP socket and never sends any private keys - all end to end 
+encryption is done transparently within the client's {@link net.i2p.client.I2PSession} 
+itself.  Periodically the router will ask the client to authorize a new set of
+tunnels to be allocated to the client, which the client can accept by sending a
+{@link net.i2p.data.LeaseSet} signed by the {@link net.i2p.data.Destination}.  In
+addition, the router may on occation provide the client with an updated clock 
+offset so that the client can stay in sync with the network (even if the host
+computer's clock is off).</p>
 </body></html>