Self-study 5

This is  self-study 5 --- Lighting.

(The source of the tutorial is https://www.youtube.com/watch?v=VnG2gOKV9dw)

Reference:

Brackeys, Lighting in Unity, <https://www.youtube.com/watch?v=VnG2gOKV9dw>.

The model of monkey and the room: <https://goo.gl/6EZjQL>.