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