[ENHANCEMENT] Add specific toml examples to the documentation

[ngblume]

Is your enhancement request related to a problem? Please describe.

I struggle with mapping the current description of several items in the config options via toml, i.e. https://robotcode.io/03_reference/config#extend-listeners...
The specification says "dict[str, list[str | StringExpression]] | None" for type, but the example is an example when not using robot.toml, but rather cli for robot itself...
I just find examples missing, of how to do it propery with robot.toml, rather than saying "does the same as original cli parameter zzz"

Describe the solution you'd like

For example, with regards to https://robotcode.io/03_reference/config#extend-listeners, I would like to have examples like such:
extend-listeners = {'AddLogStartEndTestcase' = ['arg1', 'arg2']}
which extends the existing listeners by the listener 'AddLogStartEndTestcase', passing two arguments to the listener...

Describe alternatives you've considered

n/a

Additional context

n/a