update docs

Signed-off-by: Bugen Zhao <[email protected]>

src/common/src/system_param/common.rs

@@ -19,8 +19,6 @@ use super::reader::SystemParamsReader;
 use crate::util::tracing::layer::toggle_otel_layer;
 
 /// Node-independent handler for system parameter changes.
-///
-/// Currently, it is only used to enable or disable the distributed tracing layer.
 #[derive(Debug)]
 pub struct CommonHandler;
 
@@ -34,9 +32,11 @@ impl CommonHandler {
 
     /// Handle the change of system parameters.
     pub fn handle_change(&self, diff: &SystemParamsDiff) {
+        // Toggle the distributed tracing layer.
         if let Some(enabled) = diff.enable_tracing {
             toggle_otel_layer(enabled);
         }
+        // Refresh the license key.
         if let Some(key) = diff.license_key.as_ref() {
             LicenseManager::get().refresh(key);
         }