The documentation is available as an attachment to the page that you link to (link 2): http://wiki.docbook.org/ISO690Bibliography. The direct link to the attachment is your link 3: http://wiki.docbook.org/ISO690Bibliography?action=AttachFile&do=view&target=doc.html. Both these links work for me.
However, the DocBook wiki has been slow and unreliable for some time. If you have problems with the above links, the documentation is also available as an attachment to this mailing list message: http://markmail.org/message/n2qumyhk2togibuf.