doc: update README for v3.9.0 release

This commit updates README to deprecate 3.7.x release
and pin latest release to v3.9.0

Signed-off-by: Rakshith R <rar@redhat.com>

README.md

@@ -56,10 +56,8 @@ environments.
 
 | Ceph CSI Version | Container Orchestrator Name | Version Tested|
 | -----------------| --------------------------- | --------------|
+| v3.9.0 | Kubernetes | v1.25, v1.26, v1.27|
 | v3.8.0 | Kubernetes | v1.24, v1.25, v1.26, v1.27|
-| v3.7.2 | Kubernetes | v1.22, v1.23, v1.24|
-| v3.7.1 | Kubernetes | v1.22, v1.23, v1.24|
-| v3.7.0 | Kubernetes | v1.22, v1.23, v1.24|
 
 There is work in progress to make this CO-independent and thus
 support other orchestration environments (Nomad, Mesos..etc).
@@ -69,8 +67,8 @@ NOTE:
 The supported window of Ceph CSI versions is "N.(x-1)":
 (N (Latest major release) . (x (Latest minor release) - 1)).
 
-For example, if the Ceph CSI latest major version is `3.8.0` today, support is
-provided for the versions above `3.7.0`. If users are running an unsupported
+For example, if the Ceph CSI latest major version is `3.9.0` today, support is
+provided for the versions above `3.9.0`. If users are running an unsupported
 Ceph CSI version, they will be asked to upgrade when requesting support.
 
 ## Support Matrix
@@ -130,13 +128,14 @@ in the Kubernetes documentation.
 | Ceph CSI Release/Branch | Container image name         | Image Tag |
 | ----------------------- | ---------------------------- | --------- |
 | devel (Branch)          | quay.io/cephcsi/cephcsi      | canary    |
+| v3.9.0 (Release)        | quay.io/cephcsi/cephcsi      | v3.9.0    |
 | v3.8.0 (Release)        | quay.io/cephcsi/cephcsi      | v3.8.0    |
-| v3.7.2 (Release)        | quay.io/cephcsi/cephcsi      | v3.7.2    |
-| v3.7.1 (Release)        | quay.io/cephcsi/cephcsi      | v3.7.1    |
-| v3.7.0 (Release)        | quay.io/cephcsi/cephcsi      | v3.7.0    |
 
 | Deprecated Ceph CSI Release/Branch | Container image name | Image Tag |
 | ----------------------- | --------------------------------| --------- |
+| v3.7.2 (Release)        | quay.io/cephcsi/cephcsi         | v3.7.2    |
+| v3.7.1 (Release)        | quay.io/cephcsi/cephcsi         | v3.7.1    |
+| v3.7.0 (Release)        | quay.io/cephcsi/cephcsi         | v3.7.0    |
 | v3.6.1 (Release)        | quay.io/cephcsi/cephcsi         | v3.6.1    |
 | v3.6.0 (Release)        | quay.io/cephcsi/cephcsi         | v3.6.0    |
 | v3.5.1 (Release)        | quay.io/cephcsi/cephcsi         | v3.5.1    |