added docstring to helper function import_string

sanic/config.py

@@ -4,6 +4,7 @@ import types
 from sanic.exceptions import PyFileError
 from sanic.helpers import import_string
 
+
 SANIC_PREFIX = "SANIC_"
 
 
@@ -104,6 +105,9 @@ class Config(dict):
             from yourapplication import default_config
             app.config.from_object(default_config)
 
+            or also:
+            app.config.from_object('myproject.config.MyConfigClass')
+
         You should not use this function to load the actual configuration but
         rather configuration defaults. The actual config should be loaded
         with :meth:`from_pyfile` and ideally from a location not within the