Add Play Framework and myself to README (#2997)

Author: mkurz

README.md

@@ -126,6 +126,7 @@ Thanks goes to these wonderful people for contributing to Scala Steward:
 * [Mark van der Tol](https://github.com/markvandertol)
 * [MaT1g3R](https://github.com/MaT1g3R)
 * [Mat Mannion](https://github.com/matmannion)
+* [Matthias Kurz](https://github.com/mkurz)
 * [Michael Wizner](https://github.com/mwz)
 * [Michel Daviot](https://github.com/tyrcho)
 * [miguelpuyol](https://github.com/miguelpuyol)
@@ -185,6 +186,7 @@ Consider creating PR to add your company to the list and join the community.
 * [Lightbend](https://www.lightbend.com/)
 * [Mobimeo](https://www.mobimeo.com/)
 * [Ocado Technology](https://ocadotechnology.com/)
+* [Play Framework](https://www.playframework.com/)
 * [PlayQ](https://www.playq.com/)
 * [Precog](https://precog.com/)
 * [Rewards Network](https://www.rewardsnetwork.com/)