Doc: Clusters from Scratch: Use no-quorum-policy=freeze for GFS2

Adapted from https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/configuring_and_managing_high_availability_clusters/assembly_configuring-gfs2-in-a-cluster-configuring-and-managing-high-availability-clusters.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>