add internal links for feather code

assets/css/README.md

@@ -5,3 +5,9 @@ Stylesheets
 They should not be edited directly, since they will be overwritten the next time
 the components are upgraded.  Instead, any overrides that are needed should be
 added to `_feather-custom.scss`.
+
+Tweeps can get the latest feather resources at http://go/feathercode.
+Specifically, we use:
+
+ - http://go/featherraw/feather-core/dist/css/feather-core.css
+ - http://go/featherraw/feather-component-button/dist/css/feather-component-button.css