index: add support for GNU Terry Pratchett
index: add support for GNU Terry Pratchett

A meta tag is used because Google doesn't support the
`X-Clacks-Overhead` HTTP header. http://www.gnuterrypratchett.com

dm0-/mantle,quantum/coreos-mantle,mjg59/mantle,quantum/coreos-mantle,glevand/coreos--mantle,marineam/mantle,glevand/coreos--mantle,dm0-/mantle,mjg59/mantle,mischief/mantle,mischief/mantle,marineam/mantle