Add Mastodon verification backlink

Author: Jean85

source/_layouts/base.twig

@@ -17,6 +17,7 @@
     <link rel="apple-touch-icon" href="/apple-touch-icon.png">
     <!-- Place favicon.ico in the root directory -->
 
+    <link rel="me" href="https://phpc.social/@phpfig">
     <link rel="stylesheet" href="/css/all.css?{{ site.cachebust }}">
     <link rel="stylesheet" href="/css/hljs_default.css?{{ site.cachebust }}">
     <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:300,400,400i,700,700i|Oswald|Source+Code+Pro">