content: revise description of map creation
content: revise description of map creation

Change-Id: If81d061de18fd3a8a190c04d3232e8bc247277e8
Reviewed-on: https://go-review.googlesource.com/21449
Reviewed-by: Chris Broadfoot <0c2851a4f8ab4aa5606e69c0757771dd13dbe686@golang.org>
Reviewed-by: Ralph Corderoy <d6424ecc823ca663bdcbaea8e2d9df58a4d0e2b8@inputplus.co.uk>

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