Update index.md (aframevr#5093)

added shortcut in Mac keyboard layout.

Author: karunstha

docs/introduction/index.md

@@ -129,7 +129,7 @@ running smoothly at 90fps.
 [inspector]: ./visual-inspector-and-dev-tools.md
 
 :mag: **Visual Inspector**: A-Frame provides a handy built-in [visual 3D
-inspector][inspector]. Open up *any* A-Frame scene, hit `<ctrl> + <alt> + i`,
+inspector][inspector]. Open up *any* A-Frame scene, hit `<ctrl> + <alt> + i` or `<ctrl> + <option> + i`,
 and fly around to peek under the hood!
 
 ![Inspector](https://cloud.githubusercontent.com/assets/674727/25377018/27be9cce-295b-11e7-9098-3e85ac1fe172.gif)