Add examples to waitUntil and waitFor

[jenweber]

I personally need this reminder. I keep forgetting to await and return things.

[Turbo87]

thank you!

the API.md file is automatically generated though, you will have to add those examples to the source code comments too

[scalvert]

👍 this is great. I agree we needed examples.

[jenweber]

Hi @Turbo87, this is ready for another review. Apologies for taking so long to update this. I added the examples into the source code and regenerated API.md using yarn docs. Some of the diff in the md is from preexisting changes in the source that look like they didn't get built in yet.

Let me know if anything else is needed here!

[Turbo87]

thank you 🙏