Update ddp_series_theory.rst (#3160)

Adding the correct link for the author account

Author: sekyondaMeta

beginner_source/ddp_series_theory.rst

@@ -7,7 +7,7 @@
 What is Distributed Data Parallel (DDP)
 =======================================
 
-Authors: `Suraj Subramanian <https://github.com/suraj813>`__
+Authors: `Suraj Subramanian <https://github.com/subramen>`__
 
 .. grid:: 2