Create go_codelayout.md

add go code layout rule

linkchain/go_codelayout.md

@@ -0,0 +1,85 @@
+## 代码布局
+```
+//package
+package context
+
+//import 
+import (
+    //系统库
+    "fmt"
+    "math/rand"
+    "os"
+    "time"
+
+    //项目内部库
+    linchain/xx/
+    
+    //第三方库
+    "github.com/spf13/pflag"
+    
+)
+
+//const定义
+const (
+    MaxActiveDialTasks     = 16
+)
+
+//error定义
+var (
+	ErrInvalidUnreadByte = errors.New("bufio: invalid use of UnreadByte")
+	ErrInvalidUnreadRune = errors.New("bufio: invalid use of UnreadRune")
+)
+
+//var定义
+var (
+	blockIndexBucketName = []byte("blockheaderidx")
+)
+
+/*
+    error struct定义
+*/
+type PathError struct {
+	Op   string
+	Path string
+	Err  error
+}
+
+func (e *PathError) Error() string { return e.Op + " " + e.Path + ": " + e.Err.Error() }
+
+/*
+    struct 1
+*/
+//struct定义
+type Conn struct {
+	Name  string
+}
+
+//new 定义
+func NewConn() *Conn {
+	return &Conn{}
+}
+
+//函数
+func (c *Conn) foo() bool {
+    ...
+}
+
+/*
+    struct 2
+*/
+//struct定义
+type Conn2 struct {
+	Name  string
+}
+
+//new 定义
+func NewConn2() *Conn {
+	return &Conn2{}
+}
+
+//函数
+func (c *Conn2) foo() bool {
+    ...
+}
+
+```