fix: use aside element for ideas features on ideas page

Wrap ideas feature sections within an aside, to improve accessibility
tree and scope its headings so they do not apply to the same tier as
the articles.

Author: jawinn

blocks/ideas/ideas-functions.js

@@ -22,7 +22,7 @@ import { getCurrentFiltersArray } from "../filter-group/filter-group-utils.js";
  * Create markup for ideas feature section from data/content, and return it.
  * Title text is required.
  * @param {IdeasFeatureContent} featureContent
- * @returns {HTMLDivElement|null} Markup of feature, or null if missing required content.
+ * @returns {HTMLElement|null} Markup of feature, or null if missing required content.
  */
 export const buildIdeasFeature = (featureContent) => {
   // Check for required content.
@@ -32,7 +32,7 @@ export const buildIdeasFeature = (featureContent) => {
 
   // Create markup.
   // This element is both a grid item for the larger page layout, and a grid container for its children.
-  const feature = document.createElement("div");
+  const feature = document.createElement("aside");
   feature.classList.add("grid-item", "grid-item--100", "ideas__feature");
 
   // Content side which contains text elements and button.