message: Add a small paragraph on state of the art.
diff: @@ -61,6 +61,15 @@ The heavy use of modern C++ features simplifies the addition of new executor
  paradigms and algorithmic functionality without introducing significant
  performance overhead.
  +Solving linear systems is usually one of the most computationally
  +and memory intensive aspects of any application. Hence there has been a significant
  +amount of effort in this direction with software libraries such as UMFPACK and
  +CHOLMOD[@suitesparse] for solving linear systems with direct methods and PETSc[@petsc],
  +Trilinos[@trilinos], Eigen[@eigen] and many more to solve linear systems with iterative
  +methods. With Ginkgo, we aim to ensure high performance while not compromising portability.
  +Hence, we provide very efficient low level kernels optimized for different architectures and
  +separate these kernels from the algorithms thereby ensuring extensibility and ease of use.
  +
  Ginkgo is also a part of the xSDK effort [@xsdk] and available as a Spack
  [@spack] package. xSDK aims to provide infrastructure for and interoperability
  between a collection of related and complementary software elements to foster
  