docs: remove --save from npm install; avoid system-ui (#10252)

* Minor edits for CSS doc

* Remove unnecessary --save from npm install

* Different font family
Co-authored-by: NJoe Haddad <timer150@gmail.com>

docs/basic-features/built-in-css-support.md

@@ -15,7 +15,8 @@ For example, consider the following stylesheet named `styles.css`:
 
 ```css
 body {
-  font-family: 'SF Pro Text', 'SF Pro Icons', system-ui;
+  font-family: 'SF Pro Text', 'SF Pro Icons', 'Helvetica Neue', 'Helvetica',
+    'Arial', sans-serif;
   padding: 20px 20px 60px;
   max-width: 680px;
   margin: 0 auto;

docs/getting-started.md

@@ -20,7 +20,7 @@ The interactive course with quizzes will guide you through everything you need t
 Install `next`, `react` and `react-dom` in your project:
 
 ```bash
-npm install --save next react react-dom
+npm install next react react-dom
 ```
 
 Open `package.json` and add the following `scripts`:

examples/with-stencil/packages/test-component/readme.md

@@ -61,12 +61,12 @@ Instead, use a prefix that fits your company or any name for a group of related
 
 ### Node Modules
 
-- Run `npm install my-component --save`
+- Run `npm install my-component`
 - Put a script tag similar to this `<script src='node_modules/my-component/dist/mycomponent.js'></script>` in the head of your index.html
 - Then you can use the element anywhere in your template, JSX, html etc
 
 ### In a stencil-starter app
 
-- Run `npm install my-component --save`
+- Run `npm install my-component`
 - Add an import to the npm packages `import my-component;`
 - Then you can use the element anywhere in your template, JSX, html etc

packages/next-bundle-analyzer/readme.md

@@ -5,7 +5,7 @@ Use `webpack-bundle-analyzer` in your Next.js project
 ## Installation
 
 ```
-npm install --save @next/bundle-analyzer
+npm install @next/bundle-analyzer
 ```
 
 or

packages/next-mdx/readme.md

@@ -5,7 +5,7 @@ Use [MDX](https://github.com/mdx-js/mdx) with [Next.js](https://github.com/zeit/
 ## Installation
 
 ```
-npm install --save @next/mdx @mdx-js/loader
+npm install @next/mdx @mdx-js/loader
 ```
 
 or

packages/next/bin/next.ts

@@ -7,7 +7,7 @@ import arg from 'next/dist/compiled/arg/index.js'
   } catch (err) {
     // tslint:disable-next-line
     console.warn(
-      `The module '${dependency}' was not found. Next.js requires that you include it in 'dependencies' of your 'package.json'. To add it, run 'npm install --save ${dependency}'`
+      `The module '${dependency}' was not found. Next.js requires that you include it in 'dependencies' of your 'package.json'. To add it, run 'npm install ${dependency}'`
     )
   }
 })
@@ -94,7 +94,7 @@ const React = require('react')
 
 if (typeof React.Suspense === 'undefined') {
   throw new Error(
-    `The version of React you are using is lower than the minimum required version needed for Next.js. Please upgrade "react" and "react-dom": "npm install --save react react-dom" https://err.sh/zeit/next.js/invalid-react-version`
+    `The version of React you are using is lower than the minimum required version needed for Next.js. Please upgrade "react" and "react-dom": "npm install react react-dom" https://err.sh/zeit/next.js/invalid-react-version`
   )
 }
 

packages/next/server/next-dev-server.ts

@@ -31,7 +31,7 @@ import checkCustomRoutes from '../lib/check-custom-routes'
 
 if (typeof React.Suspense === 'undefined') {
   throw new Error(
-    `The version of React you are using is lower than the minimum required version needed for Next.js. Please upgrade "react" and "react-dom": "npm install --save react react-dom" https://err.sh/zeit/next.js/invalid-react-version`
+    `The version of React you are using is lower than the minimum required version needed for Next.js. Please upgrade "react" and "react-dom": "npm install react react-dom" https://err.sh/zeit/next.js/invalid-react-version`
   )
 }
 

test/unit/handles-incorrect-react.test.js

@@ -11,7 +11,7 @@ const nextBin = path.join(nextDir, 'dist/bin/next')
 describe('Handles Incorrect React Version', () => {
   it('should throw an error when building with next', async () => {
     expect(() => require(nextBin)).toThrow(
-      /The version of React you are using is lower than the minimum required version needed for Next\.js\. Please upgrade "react" and "react-dom": "npm install --save react react-dom" https:\/\/err\.sh/
+      /The version of React you are using is lower than the minimum required version needed for Next\.js\. Please upgrade "react" and "react-dom": "npm install react react-dom" https:\/\/err\.sh/
     )
   })
 })