[RIP-9] Modify English document for Example_Orderly.md (#902)

[RIP-9] Modify English document for Example_Orderly.md

docs/en/Example_Orderly.md

@@ -4,7 +4,7 @@ RocketMQ provides ordered messages using FIFO order. All related messages need t
 
 The following demonstrates ordered messages by ensuring order of create, pay, send and finish steps of sales order process.
 
-## 2.1 produce ordered messages
+## 1 produce ordered messages
 ```
 package org.apache.rocketmq.example.order2