padoka stable ppa suggested by feral as the best way to play rise of the tomb raider

As the title indicates, Feral (linux game port developers), now recommends the padoka stable ppa when needed in the official steam game requirements page. its always nice to have ones work recognized.

stable padoka: https://launchpad.net/~paulo-miguel-dias/+archive/ubuntu/pkppa

unstable (git) padoka: https://launchpad.net/~paulo-miguel-dias/+archive/ubuntu/mesa