Add note that project is not maintained (#58)

* Add note that project is not maintained

Apologies for missing the prompt reply

This PR suggest an edit to the readme to reflect the status and let people know what to expect.

* Update README.md

Co-authored-by: Einar Löve <[email protected]>

Author: seanburlington

Diff for: README.md

@@ -1,10 +1,13 @@
-_NOTE: If you're looking for Firestore support it's on our roadmap but is currently not being worked on. Please see [the following issue](https://github.com/unfold/react-firebase/issues/50) and contribute if you can!_
-
 React Firebase
 ==============
 
 React bindings for [Firebase](https://firebase.google.com).
 
+
+__:warning: React Firebase in not maintained anymore__
+> There might come a replacement from [React itself](
+https://github.com/unfold/react-firebase/issues/57#issuecomment-644762819) with Suspense, but when is not certain. If you want to contribute or maintain this project, send a message to @einarlove.
+
 ## Installation
 
 ```