Release: add GH action to publish on NPM

[zuchka]

@stiang it looks like you were publishing this package to npm locally, or some other way?

I noticed a small typo in the sample codeblock--going to push a change for that rn, but it got me wondering about how you're publishing to NPM. If we start cutting releases more often it might be nice to integrate that step into a GH action.

reach out privately if you prefer 😄 [email protected]