[CentOS-mirror] removal of mirrors.se.kernel.org and mirrors.nl.kernel.org

[Anssi Johansson]

mirrors.se.kernel.org and mirrors.nl.kernel.org have ceased working some 
time ago. I wondered about their status on Freenode #kernel.org and I 
was told that "those are obsolete addresses. there are no EU mirrors, 
and won't be in any forseable future".

Those two mirrors (.se and .nl) should thus be removed from the CentOS 
mirror list. mirrors.kernel.org can still be used, but it's an U.S. mirror.