Great docker, thanks.
Could you add an option to select which branch to install ?
LTS Stable - All Access: 5.6.36
LTS Stable - Blog Access: 5.6.37
LTS Stable Candidate: 5.6.xx
Stable - All Access: 5.7.20 / UCK: 10.0
Stable - Blog Acess: 5.7.23 / UCK: 10.1
Stable Candidate: 5.7.xx
Testing: 5.8.xx
Thanks.