Mention cygwin support in the readme

Bruno Sutic · Bruno Sutic · commit 4ec8a9b87cec · 2015-10-08T18:19:03.000+02:00
diff --git a/README.md b/README.md
@@ -2,6 +2,8 @@
 
 Plugin for opening highlighted selection directly from Tmux copy mode.
 
+Tested and working on Linux, OSX and Cygwin.
+
 ### Key bindings
 
 In tmux copy mode:
