Add note to Volume Lifecycle figure

Author: YuikoTakada

Diff for: spec.md

@@ -210,6 +210,7 @@ creation to destruction.
 Figure 6: The lifecycle of a dynamically provisioned volume, from
 creation to destruction, when the Node Plugin advertises the
 STAGE_UNSTAGE_VOLUME capability.
+NOTE: When using Non-Graceful Node Shutdown feature in Kubernetes, status can be moved from PUBLISHED to CREATED without going through VOL_READY and/or NODE_READY status.
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