Provide information about the supported scale triggers

[tomkerkhove]

Provide information about the supported scale triggers that are available and can be deployed.

This will help:

• Developers to determine what triggers they can use in their applications
• Admins when evaluating to upgrade or not

Ideally, every supported trigger has a dedicated page with some brief information along with a list of scaled objects that are using this trigger and navigate to those.

I'm not referring to the scaled objects deployed by the customers, but more the ones we can deploy.