Add interest invoker examples to dom-examples

[chrisdavidmills]

I am currently documenting interest invokers, a feature that is available in Chrome 142 onwards. This PR adds some interest invoker demos to the repo.

[pepelsbey]

Looks good! Thank you :)

[pepelsbey]

I just realized in another review:

Maybe we should use README.md for index pages? They are rendered to HTML. For example: fetch/README.md turns into https://mdn.github.io/dom-examples/fetch/ — this will make them easier to maintain.

[chrisdavidmills]

I just realized in another review:

Maybe we should use README.md for index pages? They are rendered to HTML. For example: fetch/README.md turns into https://mdn.github.io/dom-examples/fetch/ — this will make them easier to maintain.

OK, done — does this look OK?

[pepelsbey]

Perfect! Thanks 🙂