[docs] [issue14097] Improve the "introduction" page of the tutorial

Raymond Hettinger added the comment: Please restore the section "A value can be assigned to several variables simultaneously". This is easy to teach in this context and there's no other good place to put it. Also, I'm unclear why you took out the Mark Lemburg's section on Unicode. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue14097> _______________________________________