[Mediawiki] instructions: mediawiki updates

[scott]

**** to update the mediawiki farm ****

wget new mediawiki version to the mediawiki directory:

root at orb:/opt# wget mediawiki-x.x.x.tar.gz
root at orb:/opt# md5sum mediawiki-x.x.x.tar.gz
root at orb:/opt# tar -xzvf mediawiki-x.x.x.tar.gz
root at orb:/opt# chmod root.www-data mediawiki-x.x.x
root at orb:/opt# ln -s mediawiki-x.x.x mediawiki

and that's it!