message: render <head>, not <Head>
diff: import React from 'react'
  -import Document, {Head, Main, NextScript} from 'next/document'
  +import Document, {Main, NextScript} from 'next/document'
  import {ServerStyleSheet} from 'styled-components'
  import {extractCritical} from 'emotion-server'
  import {getAssetPath} from './doc-components'
  @@ -29,10 +29,10 @@ export default class MyDocument extends Document {
  return (
  <html lang="en">
  - <Head>
  + <head>
  + <title>Primer Components</title>
  <script async src="https://www.googletagmanager.com/gtag/js?id=UA-126681523-1" />
  <script async href={getAssetPath('analytics.js')} />
  - <title>Primer Components</title>
  <meta charSet="utf8" />
  <link rel="icon" href={getAssetPath('favicon.png')} />
  <link rel="apple-touch-icon" href={getAssetPath('apple-touch-icon.png')} />
  @@ -50,7 +50,7 @@ export default class MyDocument extends Document {
  <meta property="twitter:card" content="summary_large_image" />
  <meta property="twitter:site" content="@githubprimer" />
  {styles}
  - </Head>
  + </head>
  <body>
  <Main />
  <NextScript />
  