Use /d "description" to have better file name in UAC within Windows installer

[tobiasKaminsky]

https://docs.microsoft.com/en-us/windows/win32/seccrypto/signtool#sign-command-options /d option

Needed to be changed in: https://github.com/nextcloud/client-building/blob/master/single-build-installer-msi.bat#L114