Improve comment

Author: sergerad

crates/validator/src/block_validation/mod.rs

@@ -93,7 +93,8 @@ pub async fn validate_block(
         chain_tip
     };
 
-    // Previous block commitment must match the chain tip's commitment.
+    // The proposed block's parent must match the block that the Validator has determined is its
+    // parent (either chain tip or parent of chain tip).
     if proposed_header.prev_block_commitment() != prev.commitment() {
         return Err(BlockValidationError::PrevBlockCommitmentMismatch);
     }