Fix code block formatting

source/import_documentation/build-existing-app.rst

@@ -19,19 +19,19 @@ Get the code of your app (for the example the SIB App):
 Create JON file and configure the client to contact the servers:
 
 .. code-block:: json
-{
-{
-  "xmpp": "https://jabber.happy-dev.fr/http-bind/",
-  "authority": "http://api.batman.happy-dev.fr/",
-  "clientName": "Sib App",
-  "authorityName": "batman",
-  "publicDirectory": false,
-  "endpoints": {
-    "circles": "https://api.batman.happy-dev.fr/circles/",
-    "users": "https://api.batman.happy-dev.fr/users/"
-  },
-  "analytics": []
-}
+
+    {
+      "xmpp": "https://jabber.happy-dev.fr/http-bind/",
+      "authority": "http://api.batman.happy-dev.fr/",
+      "clientName": "Sib App",
+      "authorityName": "batman",
+      "publicDirectory": false,
+      "endpoints": {
+        "circles": "https://api.batman.happy-dev.fr/circles/",
+        "users": "https://api.batman.happy-dev.fr/users/"
+      },
+      "analytics": []
+    }
 
 The parameters are: