Docs: write a guide or a blog post about documenting Javascript API with jsdoc

[humitos]

This is a small issue to track this task somewhere. The idea comes from #9241 which has a little more context.

[agjohnson]

I could take this issue as one of my doc sprints. Though JS support isn't our core focus, I think this does a good job of showing some advanced usage with build.jobs and extending our supported toolchain a bit.

There are a few guides on this configuration already, so can build on those, but there were a few RTD specific configuration bits as well.

[ericholscher]

Dupe of #11187