tutorial: update links to example source
tutorial: update links to example source

douglas-larocca/urwid,Julian/urwid,ivanov/urwid,foreni-packages/urwid,rndusr/urwid,zyga/urwid,tonycpsu/urwid,bk2204/urwid,mountainstorm/urwid,inducer/urwid,hkoof/urwid,inducer/urwid,drestebon/urwid,westurner/urwid,mountainstorm/urwid,tonycpsu/urwid,zyga/urwid,drestebon/urwid,urwid/urwid,westurner/urwid,foreni-packages/urwid,rndusr/urwid,bk2204/urwid,Julian/urwid,hkoof/urwid,drestebon/urwid,harlowja/urwid,bk2204/urwid,mountainstorm/urwid,foreni-packages/urwid,douglas-larocca/urwid,rndusr/urwid,inducer/urwid,ivanov/urwid,westurner/urwid,hkoof/urwid,harlowja/urwid,urwid/urwid,urwid/urwid,harlowja/urwid,douglas-larocca/urwid,wardi/urwid,Julian/urwid,tonycpsu/urwid,wardi/urwid,wardi/urwid,ivanov/urwid,zyga/urwid