add link to about_py

Author: HumphreyYang

lectures/about_py.md

@@ -53,7 +53,7 @@ Our only objective for this lecture is to give you some feel of what Python is,
 
 Python is free and open source, with development coordinated through the [Python Software Foundation](https://www.python.org/psf/).
 
-Python has experienced rapid adoption in the last decade and is now one of the most popular programming languages.
+Python has experienced rapid adoption in the last decade and is now one of the [most popular programming languages](https://pythoncircle.com/post/763/the-rising-popularity-of-python/).
 
 ### Common Uses