[webui] update dev doc (#4513)

ts/webui/README.md

@@ -6,15 +6,14 @@ WebUI is built by using [React](https://reactjs.org/docs/getting-started.html) a
 ## Development
 
 * Please refer the [installation doc](https://github.com/microsoft/nni#installation) to run an experiment.
-* WebUI uses [eslint](https://eslint.org/docs/user-guide/getting-started) and [prettier](https://prettier.io/docs/en/index.html) to format code. You could change the eslintrc file like this picture when you are coding.
 
-<img src="../../docs/img/webui-img/rules.png" />
-
-* Use this command in `webui/ts` directory when you want to see latest website.
+* Use this command in `webui/ts` directory when you change webui code. And then refresh website to see latest pages.
     ```bash
     yarn build
     ```
 
 ## PR
 
-* If you need to send the PR, you should change the eslintrc file back and use the command `yarn eslint` to check   style. And `yarn eslint --fix` could fix almost warnings and errors. Also use `yarn stylelint` to confirm `.scss & .css` style.
+* WebUI uses [eslint](https://eslint.org/docs/user-guide/getting-started) and [prettier](https://prettier.io/docs/en/index.html) to format code. Before you send PR, you could use the command `yarn sanity-check` to format code style.
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+
+* You could send the PR if `yarn release` gets successful build after formatting code.
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