Clarify that ConnectionFactory#setRequestedHeartbeat sets a timeout value, not communication interval

Also, link to our upcoming guide.

Author: michaelklishin

src/com/rabbitmq/client/ConnectionFactory.java

@@ -346,8 +346,9 @@ public int getShutdownTimeout() {
     }
 
     /**
-     * Set the requested heartbeat.
-     * @param requestedHeartbeat the initially requested heartbeat interval, in seconds; zero for none
+     * Set the requested heartbeat timeout. Heartbeat frames will be sent at about 1/2 the timeout interval.
+     * @param requestedHeartbeat the initially requested heartbeat timeout, in seconds; zero for none
+     * @see <a href="http://rabbitmq.com/heartbeats.html">RabbitMQ Heartbeats Guide</a>
      */
     public void setRequestedHeartbeat(int requestedHeartbeat) {
         this.requestedHeartbeat = requestedHeartbeat;