Change Display Name to "Sorayomi"

[chrigi]

Is your feature request related to a problem? Please describe.
The app's name can't be fully shown on the homescreen.

Describe the solution you'd like
Rename it from "Tachidesk Sorayomi" to simply "Sorayomi"

Describe alternatives you've considered
I think it would make sense for at least iOS and Android, not sure about the other platforms.
If you want to can create a PR for this.

Additional context