Referencing example in GuacamoleTunnelServlet.

guacamole-common/src/main/java/net/sourceforge/guacamole/servlet/GuacamoleTunnelServlet.java

@@ -317,3 +317,11 @@ public abstract class GuacamoleTunnelServlet extends HttpServlet {
 
 }
 
+/**
+ * \example ExampleTunnelServlet.java
+ *
+ * A basic example demonstrating extending GuacamoleTunnelServlet and
+ * implementing doConnect() to configure the Guacamole connection as
+ * desired.
+ */
+