Document master/seed kubernetes version support matrix

[wozniakjan]

KKP version and user-cluster kubernetes version support matrix is documented in https://docs.kubermatic.com/kubermatic/v2.22/architecture/compatibility/supported-versions

KKP master/seed requirements are documented in https://docs.kubermatic.com/kubermatic/v2.22/architecture/requirements/cluster-requirements/

But there is no docs page describing master/seed kubernetes version support. The values from go.mod can be used to give some basic idea, for example: https://github.com/kubermatic/kubermatic/blob/v2.22.2/go.mod#L105 https://github.com/kubermatic/kubermatic/blob/v2.21.2/go.mod#L120 https://github.com/kubermatic/kubermatic/blob/v2.19.0/go.mod#L85