[examples] Update react jss example (#6198)

This updates the react-jss example to work with the v10 alpha

examples/with-react-jss/package.json

@@ -7,10 +7,10 @@
     "start": "next start"
   },
   "dependencies": {
-    "next": "latest",
+    "next": "canary",
     "react": "^16.7.0",
     "react-dom": "^16.7.0",
-    "react-jss": "8.6.1"
+    "react-jss": "10.0.0-alpha.9"
   },
   "license": "ISC"
 }

examples/with-react-jss/pages/_document.js

@@ -1,15 +1,16 @@
 import React from 'react'
 import Document, { Head, Main, NextScript } from 'next/document'
-import { SheetsRegistry, JssProvider } from 'react-jss'
+import { SheetsRegistry, JssProvider, createGenerateId } from 'react-jss'
 
 export default class JssDocument extends Document {
   static async getInitialProps (ctx) {
     const registry = new SheetsRegistry()
+    const generateId = createGenerateId()
     const originalRenderPage = ctx.renderPage
     ctx.renderPage = () =>
       originalRenderPage({
         enhanceApp: App => props => (
-          <JssProvider registry={registry}>
+          <JssProvider registry={registry} generateId={generateId}>
             <App {...props} />
           </JssProvider>
         )

examples/with-react-jss/pages/index.js

@@ -1,5 +1,5 @@
 import React from 'react'
-import injectSheet from 'react-jss'
+import withStyles from 'react-jss'
 
 const styles = {
   container: {
@@ -23,4 +23,4 @@ function Index (props) {
   )
 }
 
-export default injectSheet(styles)(Index)
+export default withStyles(styles)(Index)