2 minor tag additions for doc (#192)

* Added samples showcasing XMPP

Added a number of Servlet based examples for XMPP

* Minor fixes to my previous commit

* Added couple of tags for doc

Author: meteatamel

appengine/xmpp/src/main/webapp/WEB-INF/appengine-web.xml

@@ -18,11 +18,13 @@
   <version>YOUR-VERSION-ID</version>
   <threadsafe>true</threadsafe>
 
+  <!-- [START handling_incoming_calls] -->
   <inbound-services>
     <service>xmpp_message</service>
     <service>xmpp_presence</service>
     <service>xmpp_subscribe</service>
     <service>xmpp_error</service>
   </inbound-services>
+  <!-- [END handling_incoming_calls] -->
 
 </appengine-web-app>

appengine/xmpp/src/main/webapp/WEB-INF/web.xml

@@ -25,6 +25,7 @@
     <servlet-name>error</servlet-name>
     <url-pattern>/_ah/xmpp/error/</url-pattern>
   </servlet-mapping>
+  <!-- [START messagereceiver] -->
   <servlet>
     <servlet-name>messagereceiver</servlet-name>
     <servlet-class>com.example.appengine.xmpp.MessageReceiverServlet</servlet-class>
@@ -34,6 +35,7 @@
     <url-pattern>/_ah/xmpp/message/chat/</url-pattern>
   </servlet-mapping>
   <servlet>
+  <!-- [END messagereceiver] -->
     <servlet-name>messagesender</servlet-name>
     <servlet-class>com.example.appengine.xmpp.MessageSenderServlet</servlet-class>
   </servlet>