add note about ink v6 support

Author: camfairchild

docs/wasm-contracts.md

@@ -14,6 +14,10 @@ For general smart contract development on Subtensor, please refer to the officia
 - [ink! Getting Started Guide](https://use.ink/docs/v5/getting-started/setup)
 - [ink! Examples](https://github.com/use-ink/ink-examples/tree/v5.x.x)
 
+> [!NOTE]
+> ink! `>= 6.0` drops support for `pallet-contracts`, please use `ink < 6.0`.
+> See: https://github.com/use-ink/ink/releases/tag/v6.0.0-alpha
+
 ## Subtensor-Specific Features
 
 ### Chain Extension