Update README.md

Author: mrousavy

README.md

@@ -1,7 +1,11 @@
 <div align="center">
   <img src="img/icon.png" width="30%">
   <h1>react-native-multithreading</h2>
-  <h3>🧵 Fast and easy multithreading for React Native using JSI.</h3>
+  <h3>🧵 Fast and easy multithreading for React Native using JSI. 🧵</h3>
+  <h5>
+    ⚠️ Note: This is a proof of concept. <br/>
+    Do not use this library in production.
+  </h5>
   <br/>
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