Zabbix 5.0 support for readme and zac

[ihard]

Tool zac use deprecated metods (example user.updatemedia) and not usage for configure. In the readme, the description is also for Zabbix 4 and it is not quite clear how to properly configure the integration in Zabbix 5.

[gpxlnx]

I would like this feature too.

[satterly]

Consider using Zabbix webhooks instead ... https://www.zabbix.com/documentation/current/en/manual/config/notifications/media/webhook