chore: update codeowners

add all members of code review board as default reviewers

.github/CODEOWNERS

@@ -1,3 +1,6 @@
+## Default
+* @zmstone @ieQu1 @terry-xiaoyu @qzhuyan @HJianBo @zhongwencool
+
 ## MQTT
 /apps/emqx_connector/src/mqtt/ @qzhuyan
 /apps/emqx/*/*mqtt* @qzhuyan
@@ -37,6 +40,3 @@
 /scripts/ @id
 /build    @id
 /deploy/  @id
-
-## Default
-* @zmstone