Unification of Disparate Content

[oubiwann]

This epic is continuation of the v3.0 epic: #69

All of the various forms of documentation identified in ticket #63 need to be brought into the fold:

• Pull in new Markdown docs from official LFE repo
• Convert/integrate old content from docs.lfe.io (needs ticket)
• Pull in selected Erlang stdlib HTML docs and integrate as part of the whole - Integrate selected Erlang Docs #73
• Pull in Markdown from Gitbooks

Part of release #95

[oubiwann]

We're going to ditch the docs site with all serious content going into LFE books, and general docs content going to lfe.io/docs