Mention the packages to use for web3.js version 2. (solana-labs#7417)

Author: mikemaccana

token/js/README.md

@@ -2,6 +2,11 @@
 
 A TypeScript library for interacting with the SPL Token and Token-2022 programs.
 
+> [!IMPORTANT]  
+> If you are using [@solana/web3.js version 2](https://github.com/solana-labs/solana-web3.js/?tab=readme-ov-file#whats-new-in-version-20)
+> , you should use the `@solana-program/token` and `@solana-program/token-2022` 
+> packages instead.
+
 ## Links
 
 - [TypeScript Docs](https://solana-labs.github.io/solana-program-library/token/js/)