fixup: Add method to derive Peer Storage encryption key

Co-authored-by: Matt Corallo <[email protected]>

Author: adi2011

lightning/src/sign/mod.rs

@@ -832,8 +832,8 @@ pub trait NodeSigner {
 	/// Defines a method to derive a 32-byte encryption key for peer storage.
 	///
 	/// Implementations of this method must derive a secure encryption key.
-	/// The derived key is used to encrypt or decrypt peer
-	/// storage data, ensuring confidentiality and integrity.
+	/// The key is used to encrypt or decrypt backups of our state stored with our peers.
+	/// Thus, if you wish to rely on recovery using this method, you should use a key which can be re-derived from data which would be available after state loss (eg the wallet seed)
 	///
 	/// # Implementation Details
 	///