[yt-dev] Issue #683: Update frontend documentation (yt_analysis/yt)

New issue 683: Update frontend documentation https://bitbucket.org/yt_analysis/yt/issue/683/update-frontend-documentation Matthew Turk: Currently our "frontend" documentation is somewhat out of date. We should have items describing the instantiation options for each of the frontends (including Athena). Responsible: MatthewTurk