improve comments on HA in config

karaf/config/src/main/resources/org.apache.brooklyn.osgilauncher.cfg

@@ -35,15 +35,17 @@ default.catalog.location=${karaf.etc}/default.catalog.bom
 #ignorePersistenceErrors=true
 
 # The high availability mode. Possible values are:
-# - DISABLED: management node works in isolation - will not cooperate with any other standby/master nodes in management plane;
-# - AUTO: will look for other management nodes, and will allocate itself as standby or master based on other nodes' states;
+# - AUTO: (default) will look for other management nodes, and will allocate itself as standby or master based on other nodes' states,
+#   using HOT_STANDBY as the preferred standby unless the `defaultStandbyIsHot` experimental feature is set false;
 # - MASTER: will startup as master - if there is already a master then fails immediately;
+# - DISABLED: management node works in isolation - will not cooperate with any other standby/master nodes in management plane,
+#   will assume no other nodes are using the same persisted state, and may break persistence if other nodes are;
 # - STANDBY: will start up as lukewarm standby with no state - if there is not already a master then fails immediately,
 #   and if there is a master which subsequently fails, this node can promote itself;
 # - HOT_STANDBY: will start up as hot standby in read-only mode - if there is not already a master then fails immediately,
 #   and if there is a master which subsequently fails, this node can promote itself;
 # - HOT_BACKUP: will start up as hot backup in read-only mode - no master is required, and this node will not become a master
-#highAvailabilityMode=DISABLED
+#highAvailabilityMode=AUTO
 
 # The persistence mode. Possible values are:
 # - AUTO: (default) will rebind to any existing state, or start up fresh if no state;