[about_lectures] updating link (#52)

Author: Harveyt47

source/rst/about_lectures.rst

@@ -6,4 +6,4 @@ This is one of a series of online texts on modern quantitative
 economics and programming with Python. This is the first 
 text in the series, which focuses on programming in Python. 
 
-For an overview of the series, see `this page <https://python.quantecon.org>`__
+For an overview of the series, see `this page <https://quantecon.org/python-lectures/>`__