Update web-apps.md

Author: Vamshi-Microsoft

docs/web-apps.md

@@ -36,7 +36,7 @@ TBD
 
 1. Click on `Authentication` from left menu.
 
-  ![Authentication](images/AppAuthentication.png)
+  ![Authentication](images/AppAuthentication_test.png)
 
 2. Click on `+ Add Provider` to see a list of identity providers.