Update README.md

Author: JefteCaro

README.md

@@ -14,6 +14,13 @@
 
 </div>
 
+## Contents
+* [Features](https://github.com/onesine/react-tailwindcss-datepicker/edit/master/README.md#features)
+* [Documentation](https://react-tailwindcss-datepicker.vercel.app)
+* [Installation](https://github.com/onesine/react-tailwindcss-datepicker/edit/master/README.md#installation)
+* [Simple Usage](https://github.com/onesine/react-tailwindcss-datepicker/edit/master/README.md#simple-usage)
+* [Theming Options](https://github.com/onesine/react-tailwindcss-datepicker/edit/master/README.md#theming-options)
+* [Playground](https://github.com/onesine/react-tailwindcss-datepicker/edit/master/README.md#playground)
 
 ##  Features
 - ✅ Theming options