docs: back to mathjax mode because no trusty texlive-2017 ppa
docs: back to mathjax mode because no trusty texlive-2017 ppa

FredMaris/touist,touist/touist,olzd/touist,FredMaris/touist,FredMaris/touist,touist/touist,touist/touist,olzd/touist,olzd/touist,touist/touist