Clarify README

[ghost]

(related: vmware/concord-bft#430)

Most importantly, mention the availability of DAML support (which is a strength) in commercial versions.

Rationale

• An evaluator could possibly oversee "concord" as a "too weak" product, as EVM support is usually not enough today.

• expect that some interested parties have the first-contact with VMware blockchain right here, on github.