Extensions Docs Server: Update README

chrome/common/extensions/docs/server2/README

 Overview
 
 This is a new iteration of the Chrome extension and app documentation
 server. It will replace the existing doc build system described in
 ../README.txt.
 
 As with the previous version, the goals of the system are:
 
 * Docs are generated from API definitions; it isn't possible to add or
 modify APIs without creating stub reference documentation at the same
 time.
 * Docs are editable by anyone with Chrome commit access. Docs go live
 automatically and immediately.
 * Docs are branched automatically with Chrome's source code; it's
 always possible to see the current doc for any Chrome release channel.
 
 The main difference from the previous iteration is that this server
 implements all the generation dynamically on the server, thus
 eliminating the need for annoying and error-prone generation step at
 commit time.
 
-How to Use
+
+Viewing the Docs
+
+The preview server allows easy viewing of the docs. To run the preview server:
+
+  1. Run './preview.py'
+
+  2. View docs at http://localhost:8000/(apps|extensions)/<doc_name>
+
+
+Developing the Server
+
+To run the server in the App Engine environment, follow these steps:
 
   1. Download the python Google App Engine SDK from:
      https://developers.google.com/appengine/downloads
 
-  2. Run 'start_dev_server.py <path/to/dev_appserver.py>'
+  2. Run './start_dev_server.py <path/to/dev_appserver.py>'
      (dev_appserver.py is part of the App Engine)
 
-  3. View docs at http://localhost:8080
+  3. View docs at http://localhost:8080/(apps|extensions)/<doc_name>