Update APOD extension tutorial

[jasongrout]

References

Fixes #8859

Code changes

This updates the APOD tutorial and instructions for updating it.

User-facing changes

The APOD tutorial is updated

The new tutorial repo is updated, with the update at https://github.com/jupyterlab/jupyterlab_apod/tree/3.0

I also published the new jupyterlab_apod package to reserve the name: https://pypi.org/project/jupyterlab-apod/

Backwards-incompatible changes

[jupyterlab-dev-mode]

Thanks for making a pull request to JupyterLab!

To try out this branch on binder, follow this link:

[blink1073]

Thanks for taking this on!

[blink1073]

Should we encourage publishing both so it can be used as a bundled extension?

[jasongrout]

I think not, at least in this very first tutorial. The npm publishing instructions were quite intimidating, and it was great to just cut them all out. This tutorial should focus on the simplest recommended case, I think.

I think another tutorial where you have an extension that creates a new token used by other extensions (thereby necessitating an npm publish step), or perhaps just an appendix to this tutorial talking about why you would want to publish to npm, would be good.

[blink1073]

Yeah, I like the idea of an Appendix, and listing it as an optional step

[blink1073]

But I do think it should be encouraged, because token sharing is only one reason (optimization being the other).

[jasongrout]

Can you take a look at the text I included now?

[blink1073]

Thanks!