Add a not on transform

Author: blaginin

datafusion/common/src/config.rs

@@ -30,7 +30,9 @@ use crate::{DataFusionError, Result};
 
 /// A macro that wraps a configuration struct and automatically derives
 /// [`Default`] and [`ConfigField`] for it, allowing it to be used
-/// in the [`ConfigOptions`] configuration tree
+/// in the [`ConfigOptions`] configuration tree.
+///
+/// transform is be used to normalize the value before parsing.
 ///
 /// For example,
 ///