fix: slow_sub api return field's notice_interval is missing

apps/emqx_slow_subs/etc/emqx_slow_subs.conf

@@ -25,11 +25,11 @@ emqx_slow_subs {
     ## publish is disabled if set to 0s.
     ##
     ## Value: 0s
-    expire_interval = 0s
+    notice_interval = 0s
 
     ## QoS of notification message
     ##
-    ## Defaut: 0
+    ## Default: 0
     notice_qos = 0
 
     ## Maximum information number in one notification

apps/emqx_slow_subs/src/emqx_slow_subs_schema.erl

@@ -33,7 +33,7 @@ fields("emqx_slow_subs") ->
           "QoS of notification message in notice topic")}
     , {notice_batch_size,
        sc(integer(),
-          0,
+          100,
           "Maximum information number in one notification")}
     ].