Update the readme entry to add Vesktop

[Arcitec]

The readme currently says:

ArmCord

ArmCord has arRPC specially integrated, just enable the option in its settings (server not required)!

We need the same kind of entry for Vesktop, which is the official app for Vencord. It has arRPC fully built-in/integrated too:

https://github.com/Vencord/Vesktop

In my opinion, Vesktop is by far the best and most polished alternative Discord app on Linux. So it's great that arRPC is internally integrated in it! :)

😃