Add apk signature of moshidon apk in README

Other apps that put their sha256 signing certificate on the README : - [Accrescent](https://github.com/accrescent/accrescent#signing-certificate-hash) - [Breezy Weather](https://github.com/breezy-weather/breezy-weather#download) - [NewPipe](https://github.com/TeamNewPipe/NewPipe#apk-info) - [Termux](https://github.com/termux/termux-app#github) - [SpamBlocker](https://github.com/aj3423/SpamBlocker#privacy) - [Florisboard](https://github.com/florisboard/florisboard#stable-track) - [CoMaps](https://codeberg.org/comaps/comaps#privacy) - [Obtainium](https://github.com/imranr98/obtainium) Close #662