I have no involvement in Erlang, but I just looked at that page, and as an outsider I would agree that the navigation could certainly be improved. I think a lot of the problem for me is that there is no distinction between the numbers for "Chapters" and for "Sections", and this confused me as to where I was in the progression.
Maybe using numbers for chapters, letters for sections, and a 1.A notation for the headers? At the least, adding the chapter numbers to the header, so it says "1. Introduction"? Putting the chapter numbers in the URL would help too. So would adding some highlighting in the right column index to indicate the location of the current page.
It seems like fantastic introductory material, but only if people can find it. Usually, the first thing do when I encounter a paginated manual like that is to search for a "single page" or "print" or "PDF" link. Is there one there that I couldn't find? If not, adding one might be a simple (partial) fix.
Edit: If others have more (and better) suggestions, they can be added to the issue I filed here: https://github.com/elixir-lang/elixir-lang.github.com/issues...
