Added comment

Author: matthewlipski

packages/core/src/api/exporters/html/util/serializeBlocksExternalHTML.ts

@@ -141,6 +141,8 @@ function serializeBlock<
   );
 
   if (ret.dom.classList.contains("bn-block-content")) {
+    // We wrap the output in an `li` element for list items, and so we want to
+    // add the attributes to that element instead as it is the "root".
     if (!listType) {
       for (const attr of blockContentDataAttributes) {
         (ret.dom.firstChild! as HTMLElement).setAttribute(