Update tutorial-07.md

fix typo
Merge pull request #84 from belucid/patch-1

Update tutorial-07.md
Merge branch 'tutorial-19' of https://github.com/magomimmo/modern-cljs into tutorial-19
Merge branch 'tutorial-19' of https://github.com/magomimmo/modern-cljs into tutorial-19
still working
still working