Add comment for unused/last_index

Author: Quexington

Diff for: chia/wallet/wsm_apis.py

@@ -46,9 +46,9 @@ def to_standard(self) -> CreateMorePuzzleHashesResult:
 class CreateMorePuzzleHashesResult:
     derivation_paths: list[DerivationRecord]
     mark_existing_as_used: bool
-    unused: int
+    unused: int  # The first unusued puzzle hash
     new_unhardened_keys: bool
-    last_index: int
+    last_index: int  # The index we derived up to
 
     async def commit(self, wallet_state_manager: WalletStateManager) -> None:
         if len(self.derivation_paths) > 0: