Update README.md

Author: shahar4

README.md

@@ -28,3 +28,10 @@ See [LICENSE-MIT](LICENSE-MIT) for details.
 - [Twitter](https://twitter.com/zksync)
 - [Twitter for Devs](https://twitter.com/zkSyncDevs)
 - [Discord](https://join.zksync.dev)
+
+## Disclaimer
+
+zkSync Era has been through lots of testing and audits. Although it is live, it is still in alpha state and will go
+through more audits and bug bounties programs. We would love to hear our community's thoughts and suggestions about it!
+It is important to state that forking it now can potentially lead to missing important security updates, critical
+features, and performance improvements.