add y-postgresql info to readme

README.md

@@ -272,6 +272,10 @@ A database and connection provider for Yjs based on Firestore.
   <dd>
 Persist YJS updates in your React Native app using <a href="https://github.com/OP-Engineering/op-sqlite">op-sqlite</a>, the fastest SQLite library for React Native. 
   </dd>
+  <dt><a href="https://github.com/MaxNoetzold/y-postgresql">y-postgresql</a></dt>
+  <dd>
+Provides persistent storage for a web server using PostgreSQL and is easily compatible with y-websocket.
+  </dd>
 </dl>
 
 # Ports