Update README.md

Author: vpagonis

README.md

@@ -17,7 +17,7 @@ __________________________________
 
 The following chart shows the overall organization of the book:
 
-<img width="400"
+<img width="600"
 src="https://github.com/vpagonis/Springer-R-book/blob/main/overview%20TLOSLbook.png">
 
 For a detailed Table of Contents and a Listing of the R codes, see the included pdf file: