chore: update platform annotations reference with undocumented entries (#2153)

Co-authored-by: Piotr1215 <8086638+Piotr1215@users.noreply.github.com>

Author: loft-bot

platform/reference/platform-annotations.mdx

@@ -687,6 +687,34 @@ Identifies the Kubernetes name associated with the vCluster node.
 
 Indicates the original namespace of an object synced from the vCluster to the host cluster.
 
+## Snapshot and restore {#snapshot-restore}
+
+These labels mark resources used for vCluster backup and restore operations.
+
+### vcluster.loft.sh/snapshot-request {#vcluster-loft-sh-snapshot-request}
+
+**Type:** Label
+
+**Example:** `vcluster.loft.sh/snapshot-request: "true"`
+
+**Used on:** ConfigMap, Secret
+
+**Set by:** Platform
+
+Marks ConfigMaps and Secrets as snapshot request resources for vCluster backup operations.
+
+### vcluster.loft.sh/restore-request {#vcluster-loft-sh-restore-request}
+
+**Type:** Label
+
+**Example:** `vcluster.loft.sh/restore-request: "true"`
+
+**Used on:** ConfigMap, Secret
+
+**Set by:** Platform
+
+Marks ConfigMaps and Secrets as restore request resources for vCluster restore operations.
+
 ## Auto sleep configuration {#sleep-mode-configuration}
 
 These annotations configure auto sleep behavior.