The original Learning Go is written in LaTeX. With LaTeX you get beautiful (PDF) output, but there are a few problems. Most notably I consider LaTeX an output format: it is hard to convert it into something else. Markdown offers much more flexibility in that regard. The downside of markdown is that is not powerful enough to typeset a book. To fix this I forked BlackFriday extended it and renamed it Mmark (These are all written in Golang).
Mmark is a markdown variant that is powerful enough to typeset complete books and (this is its main goal) can be used to write I-D and RFCs for the IETF.
Next I rewrote “Learning Go” in mmark, extended the HTML5 renderer, learned some jQuery and put the result online.
So… the official new, latest, most active developed version of “Learning Go” can be found on my website.