Add National Library of Wales to wgCopyUploadsDomains

This patch adds *.llgc.org.uk, the website of the
National Library of Wales (Llyfrgell Genedlaethol
Cymru), to $wgCopyUploadsDomains so as to enable
mass collection uploads on Wikimedia Commons.

Also using the opportunity to shorten description
for existing $wgCopyUploadsDomain entries which have
bugged me for a while already.

Bug: 60964
Change-Id: Ic32324971cdeb5d9940b28486afd82e99d125eae