Update src/customizer.rs

Co-authored-by: Nga Tran <[email protected]>

Author: robtandy

src/customizer.rs

@@ -3,6 +3,11 @@ use datafusion_proto::physical_plan::PhysicalExtensionCodec;
 
 #[async_trait::async_trait]
 pub trait Customizer: PhysicalExtensionCodec + Send + Sync {
-    /// Customize the context before planning a a query.
+    /// Customize the context before planning a query.
+    /// This may include registering new file formats or introducing additional 
+    /// `PhysicalPlan` operators. 
+    ///
+    /// To support serialization of customized plans for distributed execution, 
+    /// a `Codec` may also be required.
     async fn customize(&self, ctx: &mut SessionContext) -> Result<(), Box<dyn std::error::Error>>;
 }