updated readme

Author: tsung-wei-huang

README.md

@@ -23,6 +23,7 @@ All the lists in this page are either in alphabetical order or chronological ord
 - [Cpp-Taskflow: A Modern C++ Parallel Task Programming Library](https://github.com/cpp-taskflow/cpp-taskflow)
 - [FastFlow: High-performance Parallel Patterns in C++](https://github.com/fastflow/fastflow)
 - [Galois: A C++ Library to Ease Parallel Programming with Irregular Parallelism](https://github.com/IntelligentSoftwareSystems/Galois)
+- [Heteroflow: Concurrent CPU-GPU Task Programming using Modern C++](https://github.com/Heteroflow/Heteroflow)
 - [HPX: A C++ Standard Library for Concurrency and Parallelism](https://github.com/STEllAR-GROUP/hpx)
 - [Intel TBB: Threading Building Blocks](https://www.threadingbuildingblocks.org/)
 - [Kokkos: A C++ Programming Model for Writing Performance Portable Applications on HPC platforms](https://github.com/kokkos/kokkos)
@@ -54,6 +55,7 @@ All the lists in this page are either in alphabetical order or chronological ord
 
 #### Generic Parallel Computing Topics
 
+- [Concurrency in C++20 and Beyond](https://www.youtube.com/watch?v=jozHW_B3D4U) - A. Williams
 - [Is Parallel Programming still Hard?](https://www.youtube.com/watch?v=YM8Xy6oKVQg) - P. McKenney, M. Michael, and M. Wong at CppCon 2017
 - [The Speed of Concurrency: Is Lock-free Faster?](https://www.youtube.com/watch?v=9hJkWwHDDxs) - Fedor G Pikus in CppCon 2016