docs: link to docs from root readme

Author: uxduck

README.md

@@ -1,6 +1,10 @@
 # [`Push`](/push), a Flutter package for push notifications
 
-This is just a repository which contains all the packages related to `Push` federated package. Take a look at the [README](push/README.md) in the "app facing package" (`push`).
+This is a repository following the [federated plugin](https://docs.flutter.dev/packages-and-plugins/developing-packages#federated-plugins) structure.
+
+## Documentation
+
+Take a look at the [documentation](push/README.md) in the "app facing package" (`push`).
 
 ## Contributing