Previous section of documentation said that if GOPATH is not set then
it will be default to "$HOME/go", not "$HOME/work".

This change fix the path in example code to "$HOME/go", and while at it
fix the output of git command after commit.

Change-Id: Ifedca6c3997efd07e865c27b7321d755acad0254
Reviewed-on: https://go-review.googlesource.com/c/go/+/175258Reviewed-by: Andrew Bonventre <andybons@golang.org>