step one of #59 — create a new workflow that runs on a docs-preview-create repository dispatch. The idea is that every push to a PR on svelte or kit or cli will cause a preview branch to be created.

TODO

• see if this actually works (need to merge it to find out; will probably need to mess around with PATs in order to create and push branches, not sure if the provided token has those permissions)
• set up workflows on the other repos
• figure out how to add a comment on the PR with a link to the preview deployment (but only if docs were affected)
• set up a workflow to delete the branch when the PR is closed/merged