Move authors to frontmatter

[troyraen]

This moves the notebook author lists out of the "About this Notebook" sections and into the frontmatter so that they show up under the notebook titles. Also removes the generic "IRSA scientists and developers". We need to do this for the SPHEREx source discovery notebook rather quickly but we want to do it for all notebooks anyway.

It might be good to clean up a few of these author lists but I'll bring that up separately so that it doesn't hold up this PR.

[bsipocz]

While the content looks OK, both circleCI and Github has status issues, so this indeed need to wait until tomorrow -- CI to be restarted in the morning to double check the rendering.

[troyraen]

Totally fine to wait until tomorrow.

I think circleci is failing because I touched all notebooks and that causes grep -vf changed_tutorials all_tutorials to return exit code 1, which is treated as a failure. So we probably need to update tox.ini either here or in a separate pr.

[bsipocz]

I think circleci is failing because I touched all notebooks and that causes grep -vf changed_tutorials all_tutorials to return exit code 1, which is treated as a failure. So we probably need to update tox.ini either here or in a separate pr.

Oh, I thought I fixed all of those already, but now I see it's an unmerged changed in an open PR. I'll cherry-pick those changes into a separate PR.

[bsipocz]

Could you please rebase?

[bsipocz]

Rendering looks good, and CI failure is unrelated. Thanks!