Update visual-studio-2015.jade (#2416)

* Update visual-studio-2015.jade

In Step 7 (Build and Run App), there needs to be instruction to set index.html as start page, so that when Run button or F5 is pressed to run the application, browser shows index.html

* Update visual-studio-2015.jade

Author: prashantma

public/docs/ts/latest/cookbook/visual-studio-2015.jade

@@ -130,6 +130,8 @@ h2#edit-config Step 6: Edit the TypeScript configuration file
 h2#build-and-run Step 7: Build and run the app
 
 :marked
+  To set index.html as start page, right-click `index.html` in Solution Explorer and select option `Set As Start Page`.
+  
   Click the Run button or press F5 to build and run the application.
 
   This launches the default browser and runs the QuickStart sample application.