[libvirt] [docs] Couple of wiki pages with examples of live block operations

Heya, Here are some examples of live block operations (to begin with, active blockcommit) after some testing and from discussions with Eric Blake on IRC/email: http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit http://wiki.libvirt.org/page/Live-merge-an-entire-disk-image-chain-includ... I linked the above two pages here: http://wiki.libvirt.org/page/Main_Page#Examples_of_live_block_opertaions Will try to add more examples (like blockcopy, etc) and post them for review here. If you have comments/rewording/corrections you can provide here and I can update the wiki or you can just edit the wiki yourself. PS: I wondered breifly whether to post the plain text of the wiki content to the list but decided against it to keep the email brief :-) -- /kashyap