Improve documentation of configuration properties with type Map<String, NotAConfigGroup>

[yrodiere]

Description

Configuration properties of type Map<String, SomeConfigGroup>, where SomeConfigGroup is a type annotated with @ConfigGroup are handled nicely, with documentation clearly stating that the map key is included in the configuration property key:

The name of the map key in the documentation can even be customized with @ConfigDocMapKey("someName").

On the other hand, configuration properties of type Map<String, NotAConfigGroup>, where NotAConfigGroup is a type that is not annotated with @ConfigGroup, are not handled nicely at all:

Also, adding @ConfigDocMapKey("someName") on such properties has no effect.

We should display Maps the same way in the documentation, regardless of whether the value type is a config group or not.

Implementation ideas

No response

[quarkus-bot]

/cc @radcortez (config)