docs: fix instructions for adding sass

Closes: facebook#10045

docusaurus/docs/adding-a-sass-stylesheet.md

@@ -10,12 +10,12 @@ Generally, we recommend that you don’t reuse the same CSS classes across diffe
 
 Following this rule often makes CSS preprocessors less useful, as features like mixins and nesting are replaced by component composition. You can, however, integrate a CSS preprocessor if you find it valuable.
 
-To use Sass, first install `node-sass`:
+To use Sass, first install `sass`:
 
 ```sh
-$ npm install node-sass --save
+$ npm install sass -D
 $ # or
-$ yarn add node-sass
+$ yarn add sass -D
 ```
 
 Now you can rename `src/App.css` to `src/App.scss` and update `src/App.js` to import `src/App.scss`.
@@ -32,11 +32,12 @@ This will allow you to do imports like
 
 > **Note:** You must prefix imports from `node_modules` with `~` as displayed above.
 
-`node-sass` also supports the `SASS_PATH` variable.
+`sass` also supports the `SASS_PATH` variable.
 
 To use imports relative to a path you specify, and from `node_modules` without adding the `~` prefix, you can add a [`.env` file](https://github.com/facebook/create-react-app/blob/master/docusaurus/docs/adding-custom-environment-variables.md#adding-development-environment-variables-in-env) at the project root with the variable `SASS_PATH=node_modules:src`. To specify more directories you can add them to `SASS_PATH` separated by a `:` like `path1:path2:path3`.
 
 If you set `SASS_PATH=node_modules:src`, this will allow you to do imports like
+
 ```scss
 @import 'styles/colors'; // assuming a styles directory under src/, where _colors.scss partial file exists.
 @import 'nprogress/nprogress'; // importing a css file from the nprogress node module