docs: add comment explaining rawOpen usage

Clarify why rawOpen is used instead of mergedOpen to prevent
premature clearing of search input.

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: zombieJ

src/BaseSelect/index.tsx

@@ -430,7 +430,10 @@ const BaseSelect = React.forwardRef<BaseSelectRef, BaseSelectProps>((props, ref)
     onSearch(searchText, { source: 'submit' });
   };
 
-  // Close will clean up single mode search text
+  // Clean up search value when the dropdown is closed.
+  // We use `rawOpen` here to avoid clearing the search input when the dropdown is
+  // programmatically closed due to `notFoundContent={null}` and no matching options.
+  // This allows the user to continue typing their search query.
   React.useEffect(() => {
     if (!rawOpen && !multiple && mode !== 'combobox') {
       onInternalSearch('', false, false);