added preview to readme

Author: sbrichardson

README.md

@@ -1,5 +1,10 @@
 
-This is a placeholder demo project for exploring & working on react-sortable-hoc features.
+
+![Drag and Drop preview](docs/preview.gif)
+
+
+** A demo project for working on react-sortable-hoc features. **
+
 
 Based on code from [mixa9269/react-sortable-multiple-hoc](https://github.com/mixa9269/react-sortable-multiple-hoc)