docs: highlight v2 changes

Signed-off-by: Moritz Wanzenböck <[email protected]>

docs/how-to/upgrade/index.md

@@ -30,3 +30,31 @@ This guide assumes:
 [Step 2:]: ./2-collect-information.md
 [Step 3:]: ./3-remove-operator-v1.md
 [Step 4:]: ./4-install-operator-v2.md
+
+## Key Changes Between Operator V1 and V2
+
+### Administrative Changes
+
+* The resources `LinstorController`, `LinstorSatelliteSet` and `LinstorCSIDriver` have been replaced by
+  [`LinstorCluster`](../../reference/linstorcluster.md) and
+  [`LinstorSatelliteConfgiuration`](../../reference/linstorsatelliteconfiguration.md).
+* The default deployment runs the LINSTOR Satellite in the [container network](../drbd-host-networking.md).
+  The migration script will propose changing to the host network.
+
+### Operational Changes
+
+* In Operator v1, all labels on the Kubernetes node resource where replicated on the satellite, making them usable in the
+  `replicasOnSame` and `replicasOnDifferent` parameters on the storage class. In Operator v2, only the following
+  labels are automatically synchronized.
+  * `kubernetes.io/hostname`
+  * `topology.kubernetes.io/region`
+  * `topology.kubernetes.io/zone`
+  Use [`LinstorSatelliteConfiguration.spec.properties`](../../reference/linstorsatelliteconfiguration.md#specproperties)
+  to synchronize additional labels.
+* The following settings are applied by Operator v2 cluster-wide:
+  * DrbdOptions/Net/rr-conflict: retry-connect
+  * DrbdOptions/Resource/on-suspended-primary-outdated: force-secondary
+  * DrbdOptions/Resource/on-no-data-accessible: suspend-io
+  * DrbdOptions/auto-quorum: suspend-io
+* Operator v2 also includes a [High-Availability Controller](https://github.com/piraeusdatastore/piraeus-ha-controller)
+  deployment to prevent stuck nodes caused by suspended DRBD devices.