Add Javadoc to RPC timeout related classes

Fixes #219

Author: acogoluegnes

src/main/java/com/rabbitmq/client/ChannelRpcTimeoutException.java

@@ -4,12 +4,19 @@
 import java.util.concurrent.TimeoutException;
 
 /**
- *
+ * Exception thrown when a channel times out on a RPC call.
+ * @since 4.1.0
  */
 public class ChannelRpcTimeoutException extends IOException {
 
+    /**
+     * The channel that performed the RPC.
+     */
     private final Object channel;
 
+    /**
+     * The request method that timed out.
+     */
     private final Method method;
 
     public ChannelRpcTimeoutException(TimeoutException cause, Object channel, Method method) {

src/main/java/com/rabbitmq/client/ConnectionFactory.java

@@ -119,6 +119,10 @@ public class ConnectionFactory implements Cloneable {
 
     private SSLContext sslContext;
 
+    /**
+     * RPC timeout.
+     * @since 4.1.0
+     */
     private int channelRpcTimeout = DEFAULT_CHANNEL_RPC_TIMEOUT;
 
     /** @return the default host to use for connections */