head: add fediverse creator info

So people know who is behind this blog post.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

Author: matttbe

_includes/custom-head.html

@@ -6,3 +6,4 @@
 <link rel="shortcut icon" href="/assets/favicon.ico">
 <meta name="msapplication-TileColor" content="#da532c">
 <meta name="msapplication-config" content="/assets/browserconfig.xml">
+<meta name="fediverse:creator" content="@[email protected]">