Insert header

[qpfiffer]

Should auto-insert the generated header on every page:

<!--
  ____ ____  _____ ____  _   _ _   _ _   _ _  _______ _
 / ___|  _ \| ____/ ___|| | | | | | | \ | | |/ / ____| |
| |  _| |_) |  _| \___ \| |_| | | | |  \| | ' /|  _| | |
| |_| |  _ <| |___ ___) |  _  | |_| | |\  | . \| |___| |___
 \____|_| \_\_____|____/|_| |_|\___/|_| \_|_|\_\_____|_____|

Proudly generated with GRESHUNKEL, a static site generator for the dead inside.
-->