Add +docs to seeds and snapshots

[grahamwetzler]

I tested in dbt 1.7 and both seeds and snapshots support docs config in dbt_project.yml

[dave-connors-3]

spoke too soon! @grahamwetzler looks like all you'll need to do is add the same key to both spots you already added it without the + in front. We allow either "plussed" or "unplussed" configs, so we have a CI check to always makes sure we have both!