update readme

README.md

@@ -33,6 +33,7 @@ The goal of `event` is to provide a `BASIC` tool for building high performance n
 ## Getting Started
 
 ### Installing
+
 To start using `event`, just run `go get`:
 
 ```sh
@@ -47,26 +48,26 @@ $ go get -u github.com/cheng-zhongliang/event
 
 When the event is triggered, the callback function will be called.
 
-### Option
-
-The event is one-shot by default. If you want to persist, you can set the `EvPersist` option.
-
-```go
-ev := event.New(base, fd, event.EvRead|event.EvPersist, callback, arg)
-```
-
 ### Read/Write/Timeout
 
 These events can be used in combination.
 
 ```go
 base := event.NewBase()
-ev := event.New(base, fd, event.EvRead|event.Timeout|event.EvPersist, callback, arg)
+ev := event.New(base, fd, event.EvRead|event.Timeout, callback, arg)
 ev.Attach(time.Second)
 ```
 
 When the fd is readable or timeout expires, this event will be triggered.
 
+### Option
+
+The event is one-shot by default. If you want to persist, you can set the `EvPersist` option.
+
+```go
+ev := event.New(base, fd, event.EvRead|event.EvPersist, callback, arg)
+```
+
 ### Timer
 
 The timer is a one-shot event that will be triggered after the timeout expires.