UX: show date of last edit on wiki topics

app/assets/javascripts/discourse/lib/transform-post.js.es6

@@ -35,6 +35,7 @@ export function transformBasicPost(post) {
     primary_group_flair_bg_color: post.primary_group_flair_bg_color,
     primary_group_flair_color: post.primary_group_flair_color,
     wiki: post.wiki,
+    lastWikiEdit: post.last_wiki_edit,
     firstPost: post.post_number === 1,
     post_number: post.post_number,
     cooked: post.cooked,

app/assets/javascripts/discourse/widgets/post.js.es6

@@ -171,19 +171,22 @@ createWidget('post-meta-data', {
       }, iconNode('eye-slash')));
     }
 
+    const lastWikiEdit = attrs.wiki && attrs.lastWikiEdit && new Date(attrs.lastWikiEdit);
     const createdAt = new Date(attrs.created_at);
-    if (createdAt) {
-      result.push(h('div.post-info',
-        h('a.post-date', {
-          attributes: {
-            href: attrs.shareUrl,
-            'data-share-url': attrs.shareUrl,
-            'data-post-number': attrs.post_number,
-          }
-        }, dateNode(createdAt))
-      ));
+    const date = lastWikiEdit ? dateNode(lastWikiEdit) : dateNode(createdAt);
+    const attributes = {
+      class: "post-date",
+      href: attrs.shareUrl,
+      'data-share-url': attrs.shareUrl,
+      'data-post-number': attrs.post_number
+    };
+
+    if (lastWikiEdit) {
+      attributes["class"] += " last-wiki-edit";
     }
 
+    result.push(h('div.post-info', h('a', { attributes }, date)));
+
     if (attrs.via_email) {
       result.push(this.attach('post-email-indicator', attrs));
     }