Update intro.md

Author: HumphreyYang

lectures/intro.md

@@ -11,7 +11,7 @@ kernelspec:
 
 # Computational Economics and Finance for Undergraduates
 
-This website presents a set of lectures for undergraduates focusing on computational economics and finance, designed and written by [Thomas J. Sargent](http://www.tomsargent.com/) and [John Stachurski](http://johnstachurski.net/).x
+This website presents a set of lectures for undergraduates focusing on computational economics and finance, designed and written by [Thomas J. Sargent](http://www.tomsargent.com/) and [John Stachurski](http://johnstachurski.net/).
 
 For an overview of the series, see [this page](https://quantecon.org/python-lectures/)