go-tour: replace Table of Contents button
go-tour: replace Table of Contents button

The previous version was the Envy Labs logo. (Oops.)

R=r, christoph
CC=golang-dev
https://golang.org/cl/8750045

rofrol/go-tour-pl,shuLhan/go-tour-id,shuLhan/tour,raindev/tour,bbandaru/tour,ybin/tour,dupoxy/go-tour-fr,Go-zh/tour,LaPingvino/go-tour-nl,ybin/tour,shuLhan/go-tour-id,LaPingvino/go-tour-nl,Go-zh/tour,campoy/go-tour-ua,bbandaru/tour,golians/tour,bbandaru/tour,tamnd/tour,dupoxy/go-tour-fr,raindev/tour,raindev/tour,LaPingvino/go-tour-eo,tamnd/tour,golians/tour,shuLhan/tour,Jasperste/tour,Go-zh/tour,LaPingvino/go-tour-eo,shuLhan/tour,golians/tour,dupoxy/go-tour-fr,LaPingvino/go-tour-eo,scryner/tour,golang/tour,zorion/go-tour-ca,phoorichet/tour,scryner/tour,scryner/tour,rofrol/go-tour-pl,Go-zh/tour,phoorichet/tour,LaPingvino/go-tour-nl,ybin/tour,shuLhan/go-tour-id,tamnd/tour,scryner/tour,zorion/go-tour-ca,campoy/go-tour-ua,rofrol/go-tour-pl,Jasperste/tour,phoorichet/tour,campoy/go-tour-ua,Jasperste/tour