Added a Windows build status badge to the readme.

readme.md

@@ -1,5 +1,7 @@
 LÖVE is an *awesome* framework you can use to make 2D games in Lua. It's free, open-source, and works on Windows, Mac OS X and Linux.
 
+[![Build Status: Windows](https://ci.appveyor.com/api/projects/status/u1a69u5o5ej1pus4?svg=true)](https://ci.appveyor.com/project/AlexSzpakowski/love)
+
 Documentation
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