Mediator README: add organisation usage list

[shaileshp0110]

Background

Give visibility of Mediator to people who are using it. The README does not contain any details about the organizations or digital identity ecosystems that have adopted the mediator. Providing this information would enhance our understanding of interoperability

Definition of Done

List organizations that are using Mediator

Implementation details

File: https://github.com/input-output-hk/atala-prism-mediator/blob/main/README.md

[yshyn-iohk]

@shaileshp0110, @mineme0110, you can make a reference to the Identus profile page or copy/paste the icons of CSign, Blocktrust, and Socious from here: https://github.com/hyperledger-identus/.github/blob/main/profile/README.md

Could you discuss this with @FabioPinheiro and close the ticket?

[pparker]

Next step:

• @FabioPinheiro & @mineme0110 to discuss (this is a 1h-2h type task)