Add Testing Section

[MentalGear]

Thank you for the great docs so far - but a crucial part is missing: testing! Please provide best practices and a minimal example so we can use xState to the fullest: https://github.com/statelyai/docs/blob/main/docs/testing.mdx

[davidkpiano]

You're right! This is a good idea, and I will do it soon.

[davidkpiano]

https://stately.ai/docs/testing