Document project capabilities added in design time targets

[davidwengier]

We add a few capabilities in a projects design time targets, we should at least document the ones that we create (eg WPF) as disctinct from the ones that are exposed by CPS.

Documenting the ones in CPS is probably a good idea too though.

[soumya-ranjan-pratap]

Can you please assign this issue to me. I want to contribute to this issue