kv: update comments

kv/iter.go

@@ -65,7 +65,7 @@ func DecodeValue(data []byte) ([]interface{}, error) {
 }
 
 // NextUntil applies FnKeyCmp to each entry of the iterator until meets some condition.
-// It will stop when fn returns true, or iterator is invalid or occur error
+// It will stop when fn returns true, or iterator is invalid or occur error.
 func NextUntil(it Iterator, fn FnKeyCmp) error {
 	var err error
 	for it.Valid() && !fn([]byte(it.Key())) {