docs fixes

Author: AGulev

docs/index.md

@@ -105,6 +105,7 @@ function init(self)
                 print("ERROR:", message.error)
             end
         end)
+        firebase.initialize()
     end
 end
 ```

firebase/api/firebase.script_api

@@ -17,14 +17,6 @@
                 When passing this, disable creation of the default Firebase App by specifying firebase.no_auto_init in game.project
                 Valid keys in the table are api_key, app_id, database_url, messaging_sender_id, project_id, storage_bucket. All values are strings.
 
-      return:
-        - name: success
-          type: boolean
-          desc: Indicates if initialisation was successful
-        - name: error
-          type: string
-          desc: Error message if initialisation failed
-
 #*****************************************************************************************************
 
     - name: get_installation_auth_token