README.md

This implements the [p≡p Engine]'s [cryptotech] interface using [Sequoia].

  [p≡p Engine]: https://gitea.pep.foundation/pEp.foundation/pEpEngine
  [cryptotech]: https://gitea.pep.foundation/pEp.foundation/pEpEngine/src/branch/master/src/cryptotech.h
  [Sequoia]: https://sequoia-pgp.org