Add links to build training sessions.

Thanks @marin are these able to be viewed publicly from the google drive?

I don't think so. We are also dropping names there so I am not sure if it is for public consumption.

@marin the course page was moved so I created a new MR https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/6561 and added the links there. I'll close this.

closed