Assumptions need to be reformulated

[tlodderstedt]

The assumptions section matches the status before adding DC API support. I suggest to rework it.

[martijnharing]

The assumptions state that "The Issuers and Verifiers cannot pre-discover Wallet's capability" but there are cases where this is possible and/or preferable and you may want to rely on those out-of-band mechanisms to convey (some of) these capabilities.

[Sakurann]

WG discussion:

• agree to remove the first bullet point "The Issuers and Verifiers cannot pre-discover Wallet's capability"