doc: add cephfs vsg to readme

added cephfs vsg feature to the readme
https://docs.ceph.com/en/latest/
cephfs/fs-volumes/#subvolume-quiesce

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

README.md

@@ -101,6 +101,7 @@ for its support details.
 |        | Dynamically provision, de-provision File mode ROX volume  | Alpha          | >= v3.0.0          | >= v1.0.0        | Pacific (>=v16.2.0)  | >= v1.14.0         |
 |        | Dynamically provision, de-provision File mode RWOP volume | Alpha          | >= v3.5.0          | >= v1.5.0        | Pacific (>=v16.2.0)  | >= v1.22.0         |
 |        | Creating and deleting snapshot                            | GA             | >= v3.1.0          | >= v1.0.0        | Pacific (>=v16.2.0)  | >= v1.17.0         |
+|        | Creating and deleting volume group snapshot               | Alpha          | >= v3.11.0         | >= v1.9.0       | Squid   (>=v19.0.0)  | >= v1.31.0         |
 |        | Provision volume from snapshot                            | GA             | >= v3.1.0          | >= v1.0.0        | Pacific (>=v16.2.0)  | >= v1.17.0         |
 |        | Provision volume from another volume                      | GA             | >= v3.1.0          | >= v1.0.0        | Pacific (>=v16.2.0)  | >= v1.16.0         |
 |        | Expand volume                                             | Beta           | >= v2.0.0          | >= v1.1.0        | Pacific (>=v16.2.0)  | >= v1.15.0         |