Allow admins to mark links as Unreliable Sources

Let's say that users in my community regularly post links for new from CNN.
its very important to for me at least to let the user know by a tag or small message that this source is Unreliable and might be biased for a certain group, government Etc.

This will create a very healthy community and improve the trust of users in the moderators.
This must happen from the admin panel. once the admin marked the link as Unreliable source, can also add a small not that can be showing to the users why this link or source marked as Unreliable.