Add deprecation warning to the repo

Author: James Go

README.md

@@ -1,5 +1,11 @@
 <!-- THIS FILE IS AUTOGENERATED SO DON'T EDIT IT DIRECTLY -->
 <!-- EDIT "templates/README_ROOT.hbs.md" and run 'yarn generate readme' -->
+> [!CAUTION]
+> @shopify/react-native-performance is no longer maintained. The packages listed below are deprecated.
+>
+> Functionality can be replaced with more modern and maintained open source
+> projects.
+
 <p align="center">
   <img src="assets/header.png" alt="React Native Performance logo" width="650">
 </p>