Sort archive years desc

src/pages/archive.js

@@ -6,6 +6,10 @@ export default function Archive({ data }) {
 	const siteMetadata = data.site.siteMetadata;
 	const yearGroups = data.allMarkdownRemark.yearGroup;
 
+	yearGroups.sort(function(a,b) {
+		return b.year - a.year;
+	});
+
 	const yearGroupsHtml = yearGroups.map(yg => {
 		const postListItems = yg.edges.map(({node}) => {
 			return (