[Feature] Add Ratings and Comments

I think it would be a good idea to add a place for ratings and comments to each app on Flathub. It would help users to see what has worked for others and what hasn’t at a glance instead of having to research each app on their own so much, or downloading and finding it does something different than what the user had thought. This would also help users decide if downloading an app is safe. If others find it does what it says and rate it well, it likely isn’t malware. But if it doesn’t do what it says or others had malware issues, it would likely be rated low.