updated info regarding since calculation

If the since parameter is calculated in scientific notation the call will fail

Author: torkvell

example/examples_apps.py

@@ -13,6 +13,7 @@
         api.set_query_parameters({'limit': 1})
 
     # Set a limit for last 7 days
+    # NB: You might need to convert the since_unix calculation from scientific notation or set the since parameter manually
     if False:
         epoch = datetime(1970, 1, 1)
         since = timedelta(days=7)