Docs: update README.md

Author: mysticatea

README.md

@@ -1,2 +1,37 @@
 # vue-eslint-demo
-The online demo to check `eslint-plugin-vue`.
+
+The online demo to check [eslint-plugin-vue](https://github.com/vuejs/eslint-plugin-vue#readme).
+
+## ⤴️ Motivation
+
+- Let's make the reproduce code/config of bugs. It would help issue handling.
+
+## 💿 Installation
+
+Open https://mysticatea.github.io/vue-eslint-demo/
+
+- It does not support browsers which don't support ES2015.
+
+## 📖 Usage
+
+- Choose rules in sidebar to enable.
+- Input code the center area.
+- Right area shows the result of `eslint --fix`.
+- Bottom area shows the error list.
+
+## 📰 Changelog
+
+- [GitHub Releases](https://github.com/mysticatea/vue-eslint-demo/releases)
+
+## 🍻 Contributing
+
+Welcome contributing!
+
+Please use GitHub's Issues/PRs.
+
+### Development Tools
+
+- `npm run build` builds the app into `/dist` directory.
+- `npm run clean` removes `/dist` directory.
+- `npm run deploy` builds the app, then updates `gh-pages` branch, then pushes it to GitHub.
+- `npm run watch` runs the app with `webpack-dev-server`.