Update README.md

Author: jeremyhart

README.md

@@ -1,6 +1,8 @@
 # QuickLook.Plugin.HelixViewer
 A plugin for viewing 3D models in QuickLook: https://github.com/xupefei/QuickLook
 
+Supported file types: .stl, .obj, .3ds, .lwo & .ply
+
 To test without building, download [this zip][1] and unzip to `QuickLook.Plugin`-folder in install-dir (default is `C:\Users\%USERNAME%\AppData\Local\Programs\QuickLook\QuickLook.Plugin\`)
 
 This is very much in beta so feedback is much appreciated.