doc(1.8.0): add important note with things to check before upgrade

Signed-off-by: James Munson <james.munson@suse.com>

content/docs/1.8.0/important-notes/_index.md

@@ -10,6 +10,7 @@ Please see [here](https://github.com/longhorn/longhorn/releases/tag/v{{< current
   - [Environment Check Script](#environment-check-script)
 - [General](#general)
   - [Upgrade Check Events](#upgrade-check-events)
+  - [Manual Checks](#manual-checks)
   - [Install/Upgrade with Helm Controller](#installupgrade-with-helm-controller)
   - [Automatic Expansion of RWX Volumes](#automatic-expansion-of-rwx-volumes)
 - [Resilience](#resilience)
@@ -35,6 +36,12 @@ The functionality of the [environment check script](https://github.com/longhorn/
 ### Upgrade Check Events
 Longhorn performs a pre-upgrade check when upgrading with Helm or Rancher App Marketplace.  If a check fails, the upgrade will stop and the reason for the check's failure will be recorded in an event.  For more detail, see [Upgrading Longhorn Manager](../deploy/upgrade/longhorn-manager).
 
+### Manual Checks
+Not every upgrade path performs the automated checks, and some situations may not be covered by the tool.  There are also some things it is recommended to check manually, via kubectl or the UI, and either take some action or defer the upgrade until they can be fixed:
+- Ensure that all V2 engine volumes are detached and the replicas are stopped.  V2 does not yet support live upgrade.
+- Don't upgrade with a volume in "Faulted" status.  If all the replicas are deemed unusable, it is possible that they may be deleted, leading to loss of data if there is no usable backup to restore.
+- Likewise, avoid upgrading if there is a failed BackingImage.  See [Backing Image](../advanced-resources/backing-image/backing-image).
+
 ### Install/Upgrade with Helm Controller
 Longhorn also supports installation or upgrade via the HelmChart controller built into RKE2 and K3s.  It allows management in a CRD YAML chart of most of the options that would normally be passed to the `helm` command-line tool. For more details on how it works, see [Install with Helm Controller](../deploy/install/install-with-helm-controller).