The link to the ubuntu installation guide was incorrect and 404'ing.
This change updates page to point (anchor) to the install guide
section of docs.openstack.org, so it will always point to the latest
versions of the install documentation.
It also updates the deep links to the current install guides for the
past few releases.
As links continue to get outdated or we forget to add new ones, the
anchor link at the top of the page will probably still work.
Change-Id: I38299c03370936eb41992a953aa9d10b01a8396b
Closes-Bug: #1147331
4f9a3a3342