draft migration path doc from ML Model to MLM Extension

[rbavery]

This adds a migration doc that describes similarities and differences in capabilities between the ML Model Extension and the Machine Learning Model Extension. It also highlights how some field names have changed, enums have been expanded, and some fields have been removed. It notes that the ML Model Extension is not maintained and it's primary public facing implementation is deprecated.

If this is approved and merged I think we should then approve and merge #16. Once the repo ownership of https://github.com/crim-ca/mlm-extension/tree/main is changed to STAC Extensions, then I can update the links in this migration document to point to the new repo url.

I think I will need assistance from the STAC Extension maintainers to make a request to CRIM to initiate a move of the entire repo since we want to preserve stars, github history, issues, etc. cc @fmigneault

[rbavery]

Thanks for the comments @gadomski

Unfortunately I don't have the bandwidth to provide a migration script right now. There might be some nontrivial decisions to handle in the migration. But I'm happy to review and work with others on PRs. stac-model is maintained alongside the spec here https://github.com/crim-ca/mlm-extension/blob/main/README_STAC_MODEL.md

I'm happy to merge this PR after the migration. If STAC maintainers initiate that @fmigneault can you accept the invite to do so for the https://github.com/crim-ca org? I'm not sure how full repo migrations work and who initiates.

[gadomski]

I'm not sure how full repo migrations work and who initiates.

I've done it a few times (for https://github.com/stactools-packages/) but it's been a minute. I believe @fmigneault can go to https://github.com/crim-ca/mlm-extension/transfer and then choose stac-extensions as the target organization — I'd try that first, at least.

[fmigneault]

@rbavery @gadomski I believe migration would be the right way to handle the transfer to preserve stars, issues, etc. I think GitHub even defines some redirects for people using the old links (but don't quote me on that 😅). This would also allow CRIM to re-fork the stac-extensions repo to indicate appropriate redirects and maintain a mirror of the old schemas (https://crim-ca.github.io/mlm-extension/), since those are employed by existing STAC deployments.

However, once this is done (and that I get the approvals from CRIM higher ups), I will need from an admin of stac-extensions to provide the necessary permissions to adjust the settings. The migration page displays a warning that all configured protection rules will be removed during the transfer. I would like to re-enable those, and make sure @rbavery, @languith and @fmigneault (at least) have the necessary access to manage the repository.

[gadomski]

I will need from an admin of stac-extensions to provide the necessary permissions to adjust the settings.

No problem at all ... when migrated, I'll be able to add you as a maintainer of the repo so you can PR (or just YOLO change) anything as needed. You will also be able to add others as needed.