Add link to video tutorial

README.md

@@ -214,7 +214,7 @@ It [has been reported](https://github.com/evgenyneu/keychain-swift/issues/15) th
 
 Thanks to Alex Nagy from [rebeloper.com](https://rebeloper.com/) for creating this two-part [video tutorial](https://www.youtube.com/watch?v=1R-VIzjD4yo&list=PL_csAAO9PQ8bLfPF7JsnF-t4q63WKZ9O9).
 
-<a href="https://www.youtube.com/watch?v=1R-VIzjD4yo&list=PL_csAAO9PQ8bLfPF7JsnF-t4q63WKZ9O9" target="_blank"><img src='graphics/keychain_swift_video_tutorial.jpg' width='600' alt='Keychain Swift video tutorial'></a>
+<a href="https://www.youtube.com/watch?v=1R-VIzjD4yo&list=PL_csAAO9PQ8bLfPF7JsnF-t4q63WKZ9O9" target="_blank"><img src='graphics/keychain_swift_video_tutorial.jpg' width='700' alt='Keychain Swift video tutorial'></a>
 
 ## Demo app