Update cross-chain-message.mdx

Added context of being able to interop w/itself.

eg interop works for uni->opm, opm->uni, but also opm->opm, uni->uni, etc.

Author: zainbacchus

pages/stack/interop/cross-chain-message.mdx

@@ -9,7 +9,7 @@ import Image from 'next/image'
 
 # Anatomy of a cross-chain message
 
-A cross-chain message applies to any message sent across a chain. This applies to asset transfers using the [SuperchainERC20](superchain-erc20) token standard. 
+A cross-chain message applies to any message sent using Superchain interop - this includes sending across chains within an interop cluster but also chains interopping with itself. This functionality applies to asset transfers using the [SuperchainERC20](superchain-erc20) token standard. 
 
 ## How it works