Samples: provide terracost usage examples

[talset]

Provide Samples/Examples to help users to test Terracost

[xescugc]

All the libs I've seen they have an examples/ they have runnable code basically and that you just have to pass flags to modify the way it runs.

• https://github.com/hajimehoshi/ebiten/tree/main/examples
• https://github.com/go-kit/kit/tree/master/examples

I don't have others in mind RN but you see what I mean hehe.