add note on snapshot

Author: Pearl Dsilva

source/adminguide/storage/clvm.rst

@@ -239,4 +239,5 @@ vgchange lockstart sharedvg # Start the VG in shared mode
 .. note::
    It is reccommended to add CLVM / CLVM_NG storage pools as a Cluster scoped resource, so as to limited number of hosts that can access the pool for optimal performance and reliability.
    Due to the lack of support from `lvm` to provide a centralized way to query which host has the lock for a given volume, CloudStack relies on tracking this information in the database. However, if there is a drift in this information, for example due to a host failure, CloudStack will attempt to query each host for the lock status of the volume. This can lead to performance issues if there are a large number of hosts in the cluster as each host will need to be queried for each volume.
-   
+   
+   VM snapshots and incremental volume snapshot are not supported for CLVM/CLVM_NG volumes as of CloudStack 4.23.0.0.