Update GitHub Repo Archiving Guidance

[egrace479]

Add .zenodo.json to the "Recommended Files" section of the GitHub Repo Guide. This includes some editing/links between the Zenodo part of the DOI Generation page and the GitHub Repo Guide.

I also added instructions on how to add the Zenodo DOI badge to a repo. This line should perhaps be rephrased to incorporate "This only has to be done once..." under a "Pro Tip" admonition, instead of the current "Warning". Interested in your thoughts.

Closes Imageomics Guide Issue 26.

[hlapp]

Looks good. See one inline edit.

For me data are still plural, and hence metadata are too, but I realize that it is now often treated as singular, so I've left that as is (it says This metadata rather than These metadata).

[hlapp]

Suggested change

The [Zenodo JSON for BioCLIP 2](https://github.com/Imageomics/bioclip-2/blob/main/.zenodo.json) provides an example that includes a grant, references, and an associated paper (`related_identifiers`), which is also listed under `notes` [for additional citation](https://zenodo.org/records/17049307). We also recommend including [this format test workflow](https://github.com/Imageomics/Collaborative-distributed-science-guide/blob/main/.github/workflows/validate-zenodo.yaml), which will run if either the `.zenodo.json` or the workflow itself is edited.

The [Zenodo JSON for BioCLIP 2](https://github.com/Imageomics/bioclip-2/blob/main/.zenodo.json) provides an example that includes a grant, references, and an associated paper (`related_identifiers`), which is also listed under `notes` [for additional citation](https://zenodo.org/records/17049307). We also recommend including [this format validation workflow](https://github.com/Imageomics/Collaborative-distributed-science-guide/blob/main/.github/workflows/validate-zenodo.yaml), which will run if either the `.zenodo.json` or the workflow itself is edited.