Add upgrade guide

Author: SzymonPobiega

menu/menu.yaml

@@ -1432,6 +1432,8 @@
     Articles:
     - Title: Upgrade tips
       Url: servicecontrol/upgrades
+    - Title: Version 6.3 to 6.4
+      Url: servicecontrol/upgrades/6.3to6.4
     - Title: Version 5 to 6
       Url: servicecontrol/upgrades/5to6
     - Title: Version 5.1 to 5.2

servicecontrol/upgrades/6.3to6.4.md

@@ -0,0 +1,9 @@
+---
+title: Upgrade ServiceControl from Version 6.3 to Version 6.4
+summary: Instructions on how to upgrade ServiceControl from version 6.3 to 6.4
+reviewed: 2023-11-30
+isUpgradeGuide: true
+component: ServiceControl
+---
+
+This upgrade guide is only relevant for ServiceControl instances that run Azure Service Bus transport. If that is the case, follow the [transport configuration documentation](/servicecontrol/transports.md#azure-service-bus) to review the settings of the transport.