Switch language button for tour.golang.org

给页面添加一个切换中/英文的按钮

These are versions of this script where the code was updated. Show all versions.

  • v0.3 28/01/2022 gtsl: support go.dev
  • v0.2 16/11/2021 gtsl: add icon
  • v0.1 16/11/2021 Imported from URL