Update file README.rst

devices/assistants/Alexa/README.rst

+xaal.alexa
+==========
+This package provides a xAAL gateway for all Alexa devices associated to an account. 
+Right now, the gateway supports TTS. 
+
+
 Install
 =======
 - Download the remote script: https://github.com/thorsten-gehrig/alexa-remote-control
@@ -8,3 +14,14 @@ Install
 - re-run the gateway
 - done
 
+
+Notes
+=====
+The gateway provides a special Alexa (virtual) device called LastAlexa. This is the 
+lattest used device. 
+
+
+Usage
+=====
+You can trigger a xAAL scenario throught the xaal.fauxmo package. And use the LastAlexa
+device to answer to the user throught the scenario.