doc: change moment.js guide to day.js (#14)

README.md

@@ -63,11 +63,13 @@ The components that you can use are as follows: If you want to configure the `Da
 
 ## 📦 Dependency 
 
-> In the next version v1.0.0, moment.js will be replaced by day.js or date-fns
+* Moment.js
 
-* [Moment](https://momentjs.com)
+In previous versions, moment.js were used. but now it is changed to `Day.js` to because of bundle size issue (#14)
 
-`Moment` is a javascript library for Parse, validate, manipulate, and display dates and times. this component use moment library to globalize and control date. You can check the locale list through this [link](https://github.com/moment/moment/tree/develop/locale).
+* [Day.js](https://github.com/iamkun/dayjs)
+
+`Day.js` is a javascript library for Parse, validate, manipulate, and display dates and times. this component use `Day.js` library to globalize and control date. You can check the locale list through this [link](https://github.com/iamkun/dayjs/tree/dev/src/locale).
 
 ## 📲 Installation 
 
@@ -91,8 +93,8 @@ import '@y0c/react-datepicker/assets/styles/calendar.scss';
 
 // Please include the locale you want to use.
 // and delivery props to calendar component 
-// See locale list https://github.com/moment/moment/tree/develop/locale
-import 'moment/locale/ko';
+// See locale list https://github.com/iamkun/dayjs/tree/dev/src/locale 
+import 'dayjs/locale/ko';
 
 class DatePickerExample extends Component {
 
@@ -167,6 +169,10 @@ Please fork and use [https://codesandbox.io/s/pw6n17pk57](https://codesandbox.io
 * Open a new issue(Bug or Feature) on [Github](https://github.com/y0c/react-datepicker/issues/new/choose)
 * Join the [Gitter room](https://gitter.im/react-datepicker/community) to chat with other developers.
 
+## 👨‍👦‍👦 Contribution 
+
+Issue and Pull Request are always welcome! 
+
 ## 📝 License 
 MIT