Renamed AppConfig.setup to ready.

Thanks Jannis and Marc for the feedback.

Fixed #21717.

django/apps/base.py

@@ -159,7 +159,7 @@ class AppConfig(object):
             models_module_name = '%s.%s' % (self.name, MODELS_MODULE_NAME)
             self.models_module = import_module(models_module_name)
 
-    def setup(self):
+    def ready(self):
         """
-        Override this method in subclasses to run setup code.
+        Override this method in subclasses to run code when Django starts.
         """

django/apps/registry.py

@@ -105,7 +105,7 @@ class Apps(object):
             self.ready = True
 
             for app_config in self.get_app_configs():
-                app_config.setup()
+                app_config.ready()
 
     def check_ready(self):
         """