content: add Thai translation of the tour.
content: add Thai translation of the tour.

Change-Id: If6746a57c6e44648a117d196af93e49da912675e
Reviewed-on: https://go-review.googlesource.com/52750
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

Go-zh/tour,shuLhan/go-tour-id,Go-zh/tour,Go-zh/tour,shuLhan/go-tour-id,shuLhan/go-tour-id,zorion/go-tour-ca,shuLhan/tour,Go-zh/tour,dupoxy/go-tour-fr,zorion/go-tour-ca,shuLhan/tour,shuLhan/tour,dupoxy/go-tour-fr,golang/tour,dupoxy/go-tour-fr