Update README.md

Author: ocots

README.md

@@ -22,7 +22,7 @@
 [blue-url]: https://github.com/JuliaDiff/BlueStyle
 
 This repo is part of the [control-toolbox ecosystem](https://github.com/control-toolbox). 
-The control-toolbox ecosystem gathers Julia packages for mathematical control and applications. The root package is [OptimalControl.jl](https://github.com/control-toolbox/OptimalControl.jl) which aims to provide tools to modelise and solve optimal control problems with ordinary differential equations by direct and indirect methods. 
+The control-toolbox ecosystem gathers Julia packages for mathematical control and applications. The root package is [OptimalControl.jl](https://github.com/control-toolbox/OptimalControl.jl) which aims to provide tools to modelise and solve optimal control problems with ordinary differential equations by direct and indirect methods, both on CPU and GPU. 
 
 [![doc OptimalControl.jl](https://img.shields.io/badge/Documentation-OptimalControl.jl-blue)](http://control-toolbox.org/OptimalControl.jl)