Use notebook_metadata.yml in place of notebook_manifest_descriptions.txt

[troyraen]

We currently use notebook_metadata.yml to generate notebook_manifest_descriptions.txt (in deploy_to_fornax branch) for the Fornax deployment. I think we could use notebook_metadata.yml for this directly. Then we wouldn't have to generate the extra file. That would also give us more flexibility to send more information to Fornax in the future, if we decide we want that at some point. HEASARC uses this fornax-manifest.yml, so I think our notebook_metadata.yml should work fine on the fornax-images end (but I can confirm).

What do you think @bsipocz?

[bsipocz]

This issue belongs to the Fornax image repo. If Abdu is happy with a yaml instead of a txt, then it's indeed easier for us.

[troyraen]

We'll probably still need a shell command in ci_publish.yml to remove tutorials/ from all the file paths when copying the yaml to the deploy_to_fornax branch.