Proposal: Spindle schema to be able to use yaml-language-server #659

Hi,

In my GitHub Actions, I added this at the top of my files:
# yaml-language-server: $schema=https://json.schemastore.org/github-workflow.json

Would it be possible to have this for spindle? I ai crafted one in my repo for example:
https://tangled.org/mykiwi.dev/rssbase.io/blob/main/.tangled/workflow.schema.json
Used like that: https://tangled.org/mykiwi.dev/rssbase.io/blob/main/.tangled/workflows/check.yml#L1

What do you think?