Update readme

Created by: M5oul

• [enh] readme: update admin interface screenshot.
• [enh] readme: update currencies and clients:
  • Ğ1 currency is launched.
  • a testing currency is simoulaneously running.
  • Simply list Cesium, Sakia, and Silkaj websites and repositories.

Created by: coveralls

Coverage remained the same at 88.916% when pulling 78e4b691 on readme into ed65a288 on dev.