Add that CSIMigration* fallback does not work for provision operations

Author: Matthew Wong

content/en/docs/reference/command-line-tools-reference/feature-gates.md

@@ -618,8 +618,10 @@ Each feature gate is designed for enabling/disabling a specific feature:
   operations from in-tree plugins to corresponding pre-installed CSI plugins
 - `CSIMigrationAWS`: Enables shims and translation logic to route volume
   operations from the AWS-EBS in-tree plugin to EBS CSI plugin. Supports
-  falling back to in-tree EBS plugin if a node does not have EBS CSI plugin
-  installed and configured. Requires CSIMigration feature flag enabled.
+  falling back to in-tree EBS plugin for mount operations to nodes that have
+  the feature disabled or that do not have EBS CSI plugin installed and
+  configured. Does not support falling back for provision operations, for those
+  the CSI plugin must be installed and configured.
 - `CSIMigrationAWSComplete`: Stops registering the EBS in-tree plugin in
   kubelet and volume controllers and enables shims and translation logic to
   route volume operations from the AWS-EBS in-tree plugin to EBS CSI plugin.
@@ -629,9 +631,11 @@ Each feature gate is designed for enabling/disabling a specific feature:
   which prevents the registration of in-tree EBS plugin.
 - `CSIMigrationAzureDisk`: Enables shims and translation logic to route volume
   operations from the Azure-Disk in-tree plugin to AzureDisk CSI plugin.
-  Supports falling back to in-tree AzureDisk plugin if a node does not have
-  AzureDisk CSI plugin installed and configured. Requires CSIMigration feature
-  flag enabled.
+  Supports falling back to in-tree AzureDisk plugin for mount operations to
+  nodes that have the feature disabled or that do not have AzureDisk CSI plugin
+  installed and configured. Does not support falling back for provision
+  operations, for those the CSI plugin must be installed and configured.
+  Requires CSIMigration feature flag enabled.
 - `CSIMigrationAzureDiskComplete`: Stops registering the Azure-Disk in-tree
   plugin in kubelet and volume controllers and enables shims and translation
   logic to route volume operations from the Azure-Disk in-tree plugin to
@@ -641,9 +645,11 @@ Each feature gate is designed for enabling/disabling a specific feature:
   `InTreePluginAzureDiskUnregister` feature flag which prevents the registration of in-tree AzureDisk plugin.
 - `CSIMigrationAzureFile`: Enables shims and translation logic to route volume
   operations from the Azure-File in-tree plugin to AzureFile CSI plugin.
-  Supports falling back to in-tree AzureFile plugin if a node does not have
-  AzureFile CSI plugin installed and configured. Requires CSIMigration feature
-  flag enabled.
+  Supports falling back to in-tree AzureFile plugin for mount operations to
+  nodes that have the feature disabled or that do not have AzureFile CSI plugin
+  installed and configured. Does not support falling back for provision
+  operations, for those the CSI plugin must be installed and configured.
+  Requires CSIMigration feature flag enabled.
 - `CSIMigrationAzureFileComplete`: Stops registering the Azure-File in-tree
   plugin in kubelet and volume controllers and enables shims and translation
   logic to route volume operations from the Azure-File in-tree plugin to
@@ -654,8 +660,11 @@ Each feature gate is designed for enabling/disabling a specific feature:
    of in-tree AzureFile plugin.
 - `CSIMigrationGCE`: Enables shims and translation logic to route volume
   operations from the GCE-PD in-tree plugin to PD CSI plugin. Supports falling
-  back to in-tree GCE plugin if a node does not have PD CSI plugin installed and
-  configured. Requires CSIMigration feature flag enabled.
+  back to in-tree GCE plugin for mount operations to nodes that have the
+  feature disabled or that do not have PD CSI plugin installed and configured.
+  Does not support falling back for provision operations, for those the CSI
+  plugin must be installed and configured. Requires CSIMigration feature flag
+  enabled.
 - `csiMigrationRBD`: Enables shims and translation logic to route volume
   operations from the RBD in-tree plugin to Ceph RBD CSI plugin. Requires
   CSIMigration and csiMigrationRBD feature flags enabled and Ceph CSI plugin
@@ -671,18 +680,24 @@ Each feature gate is designed for enabling/disabling a specific feature:
   been deprecated in favor of the `InTreePluginGCEUnregister` feature flag which prevents the registration of in-tree GCE PD plugin.
 - `CSIMigrationOpenStack`: Enables shims and translation logic to route volume
   operations from the Cinder in-tree plugin to Cinder CSI plugin. Supports
-  falling back to in-tree Cinder plugin if a node does not have Cinder CSI
-  plugin installed and configured. Requires CSIMigration feature flag enabled.
+  falling back to in-tree Cinder plugin for mount operations to nodes that have
+  the feature disabled or that do not have Cinder CSI plugin installed and
+  configured. Does not support falling back for provision operations, for those
+  the CSI plugin must be installed and configured. Requires CSIMigration
+  feature flag enabled.
 - `CSIMigrationOpenStackComplete`: Stops registering the Cinder in-tree plugin in
   kubelet and volume controllers and enables shims and translation logic to route
   volume operations from the Cinder in-tree plugin to Cinder CSI plugin.
   Requires CSIMigration and CSIMigrationOpenStack feature flags enabled and Cinder
   CSI plugin installed and configured on all nodes in the cluster. This flag has
   been deprecated in favor of the `InTreePluginOpenStackUnregister` feature flag which prevents the registration of in-tree openstack cinder plugin.
 - `CSIMigrationvSphere`: Enables shims and translation logic to route volume operations
-  from the vSphere in-tree plugin to vSphere CSI plugin.
-  Supports falling back to in-tree vSphere plugin if a node does not have vSphere
-  CSI plugin installed and configured. Requires CSIMigration feature flag enabled.
+  from the vSphere in-tree plugin to vSphere CSI plugin. Supports falling back
+  to in-tree vSphere plugin for mount operations to nodes that have the feature
+  disabled or that do not have vSphere CSI plugin installed and configured.
+  Does not support falling back for provision operations, for those the CSI
+  plugin must be installed and configured. Requires CSIMigration feature flag
+  enabled.
 - `CSIMigrationvSphereComplete`: Stops registering the vSphere in-tree plugin in kubelet
   and volume controllers and enables shims and translation logic to route volume operations
   from the vSphere in-tree plugin to vSphere CSI plugin. Requires CSIMigration and