Update link to Rails 2.3 guides from 2.3.8 to last release 2.3.11. Maybe someone could regenerate the guides

see: https://github.com/blog/738-sidejack-prevention-phase-2-ssl-everywhere

aaaaannnddd, your beloved typo only spotted in the github colored diff no matter how many passes you did before pushing

too many people are looking for the 2.3 guides, put by now a link at the top of the home, and add the Rails version in the main header

Guides: renaming to active_record_validations_callbacks for consistency and updating links to reflect new path

guides: warn about edge guides at the top of the home preamble, and mention that only for edge guides, stable guides need no warning

guides: rewrites index and credit pages as pure HTML to avoid textilizing the rendered view, in particular we can now put a DOCTYPE in the layout