It's amazing and I will link the phpStorm/webStorm but as I am looking I am pretty sure it has been ported to all the IntelliJ products and even more.

The only down side is it's not great on looks but honestly it's a popup to tell you a shortcut so it fits well for the purpose

"Key promoter"

https://plugins.jetbrains.com/plugin/4455

Guessing they're referring to Key Promoter.

https://plugins.jetbrains.com/plugin/1003