docs(uninstall): improve the uninstall guide (#906)

provide a link to the uninstall script. 

Signed-off-by: Akhil Mohan <[email protected]>

docs/uninstall.md

@@ -33,7 +33,10 @@ The recommended steps to uninstall the OpenEBS cluster gracefully is as follows.
   kubectl get bdc -n <openebs namespace>
   ```
 
-  If present, remove the finalizer entry from the corresponding BDC.
+  If present, remove the finalizer entry from the corresponding BDC. To remove the finalizer, use the following command
+  ```
+  kubectl patch -n openebs bdc <bdc-name> -p '{"metadata":{"finalizers":null}}' --type=merge
+  ```
 
 - Ensure that no OpenEBS volume or pool pods are in terminating state . You can check the running status of Pods using the following command.
 
@@ -106,11 +109,19 @@ The recommended steps to uninstall the OpenEBS cluster gracefully is as follows.
   kubectl get bd -n <openebs namespace>
   ```
 
-  If present, remove the finalizer entry from the corresponding BD and then delete it.
+  If present, remove the finalizer entry from the corresponding BD and then delete it. To remove the finazlier, use the following command
+  ```
+  kubectl patch -n openebs bd <blockdevice-xxx> -p '{"metadata":{"finalizers":null}}' --type=merge
+  ```
 
+
 - After removing a PVC, you may find a directory `/var/openebs/` on the nodes where the replica was created having some of the volume sub-directory to store metadata info related to the volume, for example `shared-pvc-69adec76-665e-46bc-b957-2b2f58338429-target` with no content. This can be removed manually using the `rm -rf` command once you successfully uninstall the OpenEBS cluster.
 
 
+:::tip NOTE 
+An uninstall script is available [here](https://github.com/openebs/charts/blob/gh-pages/scripts/uninstall/uninstall.sh) to perform all the above steps.
+:::
+
 ## Deletion of Jiva Volumes
 
 As part of deleting the Jiva Volumes - OpenEBS launches scrub jobs for clearing the data from the nodes.  This job will be running in OpenEBS installed namespace. The completed jobs need to be cleared using the following command.