Fix: Unmentioned ImageUsage::COLOR_ATTACHMENT in the Graphics Pipeline 6.5

[anshmendiratta]

In section 6.5, the image created in section 5.1 is reused, but without ImageUsage::COLOR_ATTACHMENT. This results in the following error:

The solution is simple: just add the above flag when creating an Image.

I was unable to find any mention of this in the book or issues here that addressed this.