How do I know if a plugin supports Craft 3.1's project config?
The best I could find was searching thru a plugin's changelog in the Craft Plugin Store for something like "Added support for Craft 3.1 project config."

Super Table version 2.1.1:


Added support for Craft 3.1 project config.


Redactor version 2.2.0:


Redactor for Craft CMS now requires Craft 3.1.
Improved Project Config compatibility.