Add rake task for making someone into an admin

Running-Mastodon/Administration-guide.md

@@ -1,8 +1,16 @@
 Administration guide
-=================
+====================
 
 So, you have a working Mastodon instance... now what?
 
+## Turning into an admin
+
+The following rake task:
+
+    rails mastodon:make_admin USERNAME=alice
+
+Would turn the local user "alice" into an admin.
+
 ## Administration web interface
 
 A user that is designated as `admin = TRUE` in the database is able to access a suite of administration tools:
@@ -20,6 +28,7 @@ Your site settings are stored in the `settings` database table, and editable thr
 
 You are able to set the following settings:
 
+- Site title
 - Contact username
 - Contact email
 - Site description