Add: contribution policy

vvasilev- · vvasilev- · commit fab85cd2b6dd · 2015-05-28T09:24:00.000+03:00
diff --git a/README.md b/README.md
@@ -215,5 +215,9 @@ postcss(sprites(opts))
     });
 ```
 
+## Contributing
+
+Pull requests are welcome.
+
 ## License
 MIT © 2createStudio
