Added NSF and CODE Lab logo

Author: Abhijnan03

books/index.md

@@ -1,7 +1,7 @@
 # Introduction
 This jupyter-book provides python implementation for various concepts and algorithms related to **Surrogate Methods**. The jupyter-book has been created by the **Computational Design (CODE) Laboratory** led by **Prof. Leifur Leifsson** at **Purdue University**. This jupyter-book is intended to be used as a starting point for new users of surrogate methods to implement the concepts and algorithms for their own work. The creation of this jupyter-book is funded partly by the National Science Foundation (NSF) award number 2223732. 
 
-<img src="nsf_logo.png"/> <img src="codelablogo.png"/>
+![NSF](nsf_logo.png){:height="36px" width="36px"}
 
 ## Expected learning outcomes
 After going through this jupyter-book, the reader will: