update templates, add docs to some

contrib/templates/default/ukko.mustache

@@ -1,6 +1,12 @@
+{{!
+  ukko.mustache -- overboard, contains the last threads posted regardless of newsgroup
+  template parameters:
+  - prefix ( site prefix )
+  - threads ( a list of Thread Models that represent the latest threads )
+}}
 <html>
   <head>
-    <title> ukko </title>
+    <title> ukko / overboard </title>
     <meta charset="utf-8" />
     <link rel="stylesheet" href="{{prefix}}static/site.css"></link>
   </head>