improved docs

docs/ChangelogCN.md

@@ -4,7 +4,7 @@
 	新特性:
 	* 移动xorm cmd [github.com/go-xorm/cmd](github.com/go-xorm/cmd)
 	* 在重构一般DB操作核心库 [github.com/go-xorm/core](https://github.com/go-xorm/core)
-	* 移动测试github.com/复XORM/测试 [github.com/go-xorm/tests](github.com/go-xorm/tests)
+	* 移动测试github.com/XORM/tests [github.com/go-xorm/tests](github.com/go-xorm/tests)
 
 	改进：
 	* Prepared statement 缓存

docs/QuickStart.md

@@ -693,7 +693,7 @@ Please visit [https://github.com/go-xorm/xorm/tree/master/examples](https://gith
 <a name="160"></a>
 ## 15.FAQ 
 
-1.How the xorm tag use both with json?
+* How the xorm tag use both with json?
   
   Use space.
 
@@ -702,3 +702,38 @@ type User struct {
     Name string `json:"name" xorm:"name"`
 }
 ```
+
+* Does xorm support composite primary key?
+
+  Yes. You can use pk tag. All fields have tag will as one primary key by fields order on struct. When use, you can use xorm.PK{1, 2}. For example: `Id(xorm.PK{1, 2})`.
+
+* How to use join？
+
+  We can use Join() and extends tag to do join operation. For example:
+
+    type Userinfo struct {
+        Id int64
+        Name string
+        DetailId int64
+    }
+
+    type Userdetail struct {
+        Id int64
+        Gender int
+    }
+
+    type User struct {
+        Userinfo `xorm:"extends"`
+        Userdetail `xorm:"extends"`
+    }
+
+    var users = make([]User, 0)
+    err := engine.Table(&Userinfo{}).Join("LEFT", "userdetail", "userinfo.detail_id = userdetail.id").Find(&users)
+
+    //assert(User.Userinfo.Id != 0 && User.Userdetail.Id != 0)
+
+Of course, If join statment is very long, you could directly use Sql():
+
+    err := engine.Sql("select * from userinfo, userdetail where userinfo.detail_id = userdetail.id").Find(&users)
+
+    //assert(User.Userinfo.Id != 0 && User.Userdetail.Id != 0)

docs/QuickStartCN.md

@@ -830,6 +830,32 @@ money float64 `xorm:"Numeric"`
 
 答：支持。在定义时，如果有多个字段标记了pk，则这些字段自动成为复合主键，顺序为在struct中出现的顺序。在使用Id方法时，可以用`Id(xorm.PK{1, 2})`的方式来用。
 
+* xorm如何使用Join？
+
+答：一般我们配合Join()和extends标记来进行，比如我们要对两个表进行Join操作，我们可以这样：
+
+	type Userinfo struct {
+		Id int64
+		Name string
+		DetailId int64
+	}
+
+	type Userdetail struct {
+		Id int64
+		Gender int
+	}
+
+	type User struct {
+		Userinfo `xorm:"extends"`
+		Userdetail `xorm:"extends"`
+	}
+
+	var users = make([]User, 0)
+	err := engine.Table(&Userinfo{}).Join("LEFT", "userdetail", "userinfo.detail_id = userdetail.id").Find(&users)
+
+当然，如果Join语句比较复杂，我们也可以直接用Sql函数
+
+	err := engine.Sql("select * from userinfo, userdetail where userinfo.detail_id = userdetail.id").Find(&users)
 
 <a name="170" id="170"></a>
 ## 17.讨论