Add example of defining frames by quad input.

[nojaf]

Please describe what issue(s) this PR fixes.

I was a bit confused yesterday about defining frames of a sprite by direct input using Quad. Wanted to add an example for further users.

Summary

• [ ] Changeloged

Let me know if this needs a changelog.

[amyspark-ng]

i don't think changelog for examples is necessary

[lajbel]

I don't know if it's really how it should work

[nojaf]

Another thing that could have helped me is an ArgumentException in https://github.com/kaplayjs/kaplay/blob/b5f7cfde0af2bb1b648e30c7d91e3217d88db6a1/src/math/math.ts#L100-L105 if any of these values were not between 0 and 1. Not sure if that comes with a performance cost though.