Added short threads series.

README.md

@@ -817,6 +817,7 @@ You'll get more graph practice in Skiena's book (see Books section below) and th
             - How context switching is initiated by the operating system and underlying hardware
     - [x] threads in C++ (series - 10 videos): https://www.youtube.com/playlist?list=PL5jc9xFGsL8E12so1wlMS0r0hTQoJL74M
     - [x] concurrency in Python:
+        - [x] Short series on threads: https://www.youtube.com/playlist?list=PL1H1sBF1VAKVMONJWJkmUh6_p8g4F2oy1
         - [x] Python Threads: https://www.youtube.com/watch?v=Bs7vPNbB9JM
         - [x] Understanding the Python GIL (2010): https://www.youtube.com/watch?v=Obt-vMVdM8s
             - reference: http://www.dabeaz.com/GIL