The Bruno collection docs mislabeled the rating system and referenced
endpoints that do not exist.
- Update Media Rating.yml: the rating value is a 1-10 integer scale
(displayed as 1-5 stars with half-star precision), not "typically 1-5".
- opencollection.yml: the rating routes live under
/api/media-items/:id/rating (not /api/ratings/:media_id), GET returns
null (not 0) when unrated, and document the PUT upsert route. Correct
the scale to 1-10 here as well.