Update README.md

Author: luanshixia

README.md

@@ -8,6 +8,8 @@ We temporarily provide sources and binaries for AutoCAD R18 (2010, 2011, 2012) a
 
 View [Test.cs](https://github.com/luanshixia/AutoCADCodePack/blob/master/AutoCADCommands/Test.cs) for API usage examples.
 
+## Modules
+
 The library consists of the following modules:
 
 * `Draw` to directly draw entities (with AutoCAD-command-like functions)
@@ -23,6 +25,8 @@ The library consists of the following modules:
 * `SymbolPack` to help you draw symbols like arrows, etc.
 * `IronPython` to allow you use IronPython in AutoCAD
 
+## A Quick Look
+
 You may write this elegant code with the code pack:
 
 ```csharp
@@ -83,4 +87,6 @@ public static void PolyClean0_Old()
 }
 ```
 
+## Examples
+
 View [Test.cs](https://github.com/luanshixia/AutoCADCodePack/blob/master/AutoCADCommands/Test.cs) for detailed API usage examples.