refine the content

@@ -15,12 +15,14 @@ For the wiki for SRS/3.0, please read [Chinese][srs_CN] or [English][srs_EN].
 
 * [About](#about)
 * [Usage](#usage)
-  * [Wiki](#wiki)
+  * [Wiki for v3.0](#srs-30-wiki)
+  * [Wiki for v2.0](#srs-20-wiki)
+  * [Wiki for v1.0](#srs-10-wiki)
 * [Product](#product)
   * [History](#history)
-    * [v3.0 changes](#v3)
-    * [v2.0 changes](#v2)
-    * [v1.0 changes](#v1)
+    * [v3.0 changes](#v3-changes)
+    * [v2.0 changes](#v2-changes)
+    * [v1.0 changes](#v1-changes)
   * [Releases](#releases)
   * [Features](#features)
   * [Compare](#compare)
@@ -133,7 +135,7 @@ The changes `history`, `features`, `compare`, `release` and `performance` of SRS
 
 ### History
 
-#### v3
+#### V3 changes
 
 * v3.0, 2016-12-15, fix #717, #691, http api/static/stream support cors. 3.0.9
 * v3.0, 2016-12-08, support log rotate signal SIGUSR1. 3.0.8
@@ -149,7 +151,7 @@ The changes `history`, `features`, `compare`, `release` and `performance` of SRS
 * v3.0, 2015-08-28, fix [#471][bug #471], api response the width and height. 3.0.2
 * v3.0, 2015-08-25, fix [#367][bug #367], support nginx-rtmp exec. 3.0.1
 
-#### v2
+#### V2 changes
 
 * <strong>v2.0, 2016-12-13, [2.0 beta3(2.0.223)][r2.0b3] released. 86685 lines.</strong>
 * <strong>v2.0, 2016-11-09, [2.0 beta2(2.0.221)][r2.0b2] released. 86691 lines.</strong>
@@ -291,7 +293,7 @@ The changes `history`, `features`, `compare`, `release` and `performance` of SRS
 * v2.0, 2014-10-18, remove supports for OSX(darwin). 2.0.1.
 * v2.0, 2014-10-16, revert github srs README to English. 2.0.0.
 
-#### v1
+#### V1 changes
 
 * <strong>v1.0, 2014-12-05, [1.0 release(1.0.10)][r1.0r0] released. 59391 lines.</strong>
 * <strong>v1.0, 2014-10-09, [1.0 beta(1.0.0)][r1.0b0] released. 59316 lines.</strong>