add contribution guide

Author: mkg0

CONTRIBUTING.md

@@ -0,0 +1,22 @@
+# Contributing Guide
+
+Make sure your issue or feature doesn't have any related issue at [react-date-range repo](https://github.com/Adphorus/react-date-range/issues). If it didn't exist already, create an issue.
+
+## Getting Started
+
+1. First install [Node.js](https://nodejs.org/en/download) and [Yarn](https://yarnpkg.com/lang/en/).
+
+2. Fork the project, clone your local and create a new branch which named like `fix/{bug-description}` or `feature/{feature-description}`.
+
+3. Run `yarn` to install the dependencies.
+
+4. Run `yarn dev` to start development server.
+
+## Building
+
+. Run `run test` and `run lint` for make sure tests passes and linter doesn't throw any error.
+
+. Run `yarn build` compile the library and demo source.
+
+. Push your changes and create a PR and apply code review decisions.
+