fix legacy DirectCSI upgrade documentation

Signed-off-by: Bala.FA <bala@minio.io>

docs/faq.md

@@ -18,6 +18,9 @@ You need to have necessary privileges and permissions to perform installation. G
 ### After upgrading DirectPV to v4.x.x, I do not find `direct-csi-min-io` storage class. Why?
 Legacy DirectCSI is deprecated including storage class `direct-csi-min-io` and it is no longer supported. Previously created volumes continue to work normally. For new volume requests, use the `directpv-min-io` storage class.
 
+### DirectPV installation fails with error message like _Error; unable to get legacy drives; conversion webhook for direct.csi.min.io/v1beta3, ..._ or similar. Why?
+Installing DirectPV also tries to upgrade legacy DirectCSI. Upgrading DirectCSI older than v3.1.0 requires _Conversion webhook_ service running. For appropriate upgrade process, refer [this documentation](./upgrade.md#upgrade-legacy-directcsi-csi-driver)
+
 ### In the YAML output of `discover` command, I do not find my storage drive(s). Why?
 DirectPV ignores drives that meet any of the below conditions:
 * The size of the drive is less than 512MiB.

docs/upgrade.md

@@ -21,14 +21,18 @@ Follow the below steps for an in-place upgrade
 $ curl -sfL https://github.com/minio/directpv/raw/master/docs/tools/install.sh | sh - apply
 ```
 
-### Upgrade legacy DirectCSI CSI driver v3.x.x and v2.0.9
+### Upgrade legacy DirectCSI CSI driver
 Follow the below steps to upgrade to the latest DirectPV CSI driver from a legacy DirectCSI installation.
-1. Uninstall legacy DirectCSI CSI driver.
+1. Uninstall DirectCSI driver if you run v3.1.0 or newer version. For other versions, skip this step.
 ```sh
 $ kubectl directcsi uninstall
 ```
 2. Install the latest DirectPV plugin by [this documentation](./installation.md#directpv-plugin-installation) or upgrade existing DirectPV plugin by [this documentation](#upgrade-directpv-plugin).
 3. Install the latest DirectPV CSI driver by [this documentation](./installation.md#directpv-csi-driver-installation).
+4. Uninstall DirectCSI driver if you run older than v3.1.0 version. For other versions, skip this step.
+```sh
+$ kubectl directcsi uninstall
+```
 
 ## Upgrade DirectPV plugin