Updated README.md with build information

Author: NikolayIT

README.md

@@ -7,6 +7,12 @@ Initially the project was started by **yuansfu**, last updated on `Apr 6, 2013`
 
 The development of the project is dead so here I will continue to support the code and will provide NuGet packages for easier installation.
 
+## Build
+
+[![Build status](https://ci.appveyor.com/api/projects/status/ts22h5vdkjej9j25?svg=true)](https://ci.appveyor.com/project/NikolayIT/rtfdomparser)
+
+**NuGet:** https://www.nuget.org/packages/RtfDomParser/
+
 ## Features
 * Parse RTF and generate dom tree.
 * Support image , table , multi-nested table , textbox , shape , cell merge.