Added NSF and CODE Lab logo

Author: Abhijnan03

books/images/codelablogo.png books/codelablogo.pngbooks/images/codelablogo.png renamed to books/codelablogo.png

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 # 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="./images/nsf_logo.png"/> <img src="./images/codelablogo.png"/>
+<img src="nsf_logo.png"/> <img src="codelablogo.png"/>
 
 ## Expected learning outcomes
 After going through this jupyter-book, the reader will: