Improve description, metadata and icon

addon.xml

 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <addon id="script.spotify.screensaver"
     name="Spotify Screensaver"
-    version="0.0.2"
+    version="0.0.3"
     provider-name="Benoît Harrault">
     <requires>
         <import addon="xbmc.python" version="2.25.0"/>
@@ -16,8 +16,8 @@
         <summary lang="en">A Spotify screensaver, plugged to raspotify/librespot</summary>
         <summary lang="fr">Un écran de veille Spotify, connecté à raspotify/librespot</summary>
 
-        <description lang="en">A Spotify screensaver, plugged to raspotify/librespot</description>
-        <description lang="fr">Un écran de veille Spotify, connecté à raspotify/librespot</description>
+        <description lang="en">A Spotify screensaver, plugged to raspotify/librespot. Need to install raspotify first: https://dtcooper.github.io/raspotify/</description>
+        <description lang="fr">Un écran de veille Spotify, connecté à raspotify/librespot. Nécessite d'installer raspotify en premier : https://dtcooper.github.io/raspotify/</description>
 
         <assets>
             <icon>resources/icon.png</icon>