go-tour: nudge "Go" index button over a tad
go-tour: nudge "Go" index button over a tad

This is a precursor to adding a Google Feedback link to the tour.

R=golang-dev, dsymonds
CC=golang-dev
https://codereview.appspot.com/10335043

Go-zh/tour-old,minux/go-tour-zh,Go-zh/tour-old,minux/go-tour-zh