Update Readme file

README.md

 # Traxivi
 
 This extension is to integrate CiviCRM with [Traxy](https://gitlab.wemove.eu/wemove/traxy).
-It provides a hook to store all trackable URLs created by CiviCRM in a Redis table (to be read by Traxy),
-and an AMQP consumer to store the click and open counts of CiviCRM mailings.
 
 The extension is licensed under [AGPL-3.0](LICENSE.txt).
 
+## Features
+
+The extension provides a hook to store all trackable URLs created by CiviCRM in a Redis table (to be read by Traxy),
+and API functions to store the click and open counts of CiviCRM mailings.
+These functions expect the JSON messages generated by Traxy on URL visits and opens, you can use the Rabbitizen extension
+to process these messages from RabbitMQ queues.
+
+The extension also provides an API function `Traxy.reloadcache` to initialise or fully-reload the Traxy cache,
+that you should call if the cache gets out of sync. Make sure to call this function after installing or enabling the extension.
+
 ## Installation
 
 ### Requirements
@@ -35,8 +43,11 @@ cv en traxivi
 ## Getting Started
 
  * Make sure Traxy and CiviCRM point to the same Redis database
- * Configure your reverse proxy so that extern/url.php is served by Traxy
+ * Install the extension
+ * Call `Traxy.reloadcache` API
+ * Configure your reverse proxy so that extern/url.php extern/open.php are served by Traxy
 
 ## Known Issues
 
  * Traxy must use the default prefix (not configurable yet in this extension)
+ * Due to a technical limitation of CiviCRM, the Traxy cache cannot be automatically initialised when installing or enabling the extension.