tour: hamburger menu

[Kur-Ich]

Context: https://tour.golang.org/welcome/1

I'm coding with the Tour of Go open to look up syntax, however it is very annoying to click each time several times to get through the menu. The menu also covers the code examples which is again annoying.

It would be handy to have all the topics in a long menu open continuously so that it is easy to navigate through the tour between topics. Currently it is set-up to read from one topic to the next page but not to jump around from topic to topic randomly.