Foreman 1.5 manual

I've merged the "1.5-wip" branch into gh-pages and so the 1.5 manual in
its current interim state is now published on the website.

The list of things we need to document remains here:

Thanks to anybody who can help! PRs to the same repo, on gh-pages.

For 1.5 generally I'm hoping to start the first RC in about two weeks.

··· -- Dominic Cleal Red Hat Engineering