MySQL example should allow for / provide for the use of xtrabackup

[pcrews]

What would you like to be added:
The MySQL example should allow for / provide for the ability to use xtrabackup as the backup solution instead of mysqldump

Why is this needed:
Once a database grows beyond a certain size, xtrabackup becomes a more useful / performant backup and restore option. mysqldump remains a useful tool and should be readily available, but hot backups are very much a requirement for production workloads.