Meta: docs updates

[mcous]

Overview

We've got a few tickets open that require docs updates over in testing-library/testing-library-docs. This is a meta-ticket to help me track them all

Docs updates

• Testing slots? #48
  • Add an example using a wrapper component
• How to test two way data-binding? #117
  • Add an example using a wrapper component
• How to test events being fired #178
  • Add an example using vi.fn() spies
• typescript & documentation #211
  • Investigate and fix example
• onMount isn't called when rendering components  #222
  • Add resolve.conditions to Vitest setup docs
• Failed to setup jest with Svelte4 and @testing-library/svelte #252
  • Update Jest setup docs to use ESM
• feat(vitest): add vitest cleanup export #294
  • Update Vitest docs to use @testing-library/svelte/vitest for cleanup

[mcous]

Opened testing-library/testing-library-docs#1360 to address a batch of these

[mcous]

@yanick I've opened testing-library/testing-library-docs#1366 to close out the remaining docs tickets