The source for these documents is available from Launchpad, https://launchpad.net/bzr-migration-docs. If you would like to improve them, please report a bug using that link. Better still, grab the source from there, make the edits you want to see and submit a merge proposal.
The source are reStructuredText and are build with Sphinx : you will need a 0.6.x series version. The main respository version on Ubuntu Jaunty is 0.5.2, so the easiest way to get it is to install python-setuptools and:
$ easy_install -U Sphinx