Add docs for Chat, and document callout, legend, inline list, and footer classes (#2887)

shared/data/docs.json

@@ -200,6 +200,10 @@
 							"title": "Chart",
 							"url": "/ui/components/chart"
 						},
+						{
+							"title": "Chat",
+							"url": "/ui/components/chat"
+						},
 						{
 							"title": "Countup",
 							"url": "/ui/components/countup"