Add activation flags cluster note (hashicorp#28399)

website/content/docs/release-notes/1.17.0.mdx

@@ -26,6 +26,7 @@ description: |-
 | Known Issue (0.7.0+)           | [Duplicate identity groups created](/vault/docs/upgrading/upgrade-to-1.17.x#duplicate-identity-groups-created-when-concurrent-requests-sent-to-the-primary-and-pr-secondary-cluster)
 | Known Issue (0.7.0+)           | [Manual entity merges fail](/vault/docs/upgrading/upgrade-to-1.17.x#manual-entity-merges-sent-to-a-pr-secondary-cluster-are-not-persisted-to-storage)
 | Known Issue (1.17.3-1.17.4)    | [Some values in the audit logs not hmac'd properly](/vault/docs/upgrading/upgrade-to-1.17.x#client-tokens-and-token-accessors-audited-in-plaintext)
+| Known Issue (1.17.0-1.17.5)    | [Cached activation flags for secrets sync on follower nodes are not updated](/vault/docs/upgrading/upgrade-to-1.17.x#cached-activation-flags-for-secrets-sync-on-follower-nodes-are-not-updated)
 
 ## Vault companion updates