Updated docs/emacs

  * emacs.org: set explicit hook for git-mode, in short: get rid of
    'flyspell-mode', due to bug with flyspell
    [[http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15151]]
    this is feasible decision;
  * (TOP)/emacs.d/magit-us.el: updated, tangled from Org document.