Add some links to documentation (#5251)

* Add GitHub link to header

* Add GitHub link to footer

* Add link to Stack Overflow

* Add Twitter link

* Add the repoUrl prop to the siteConfig

* Switch out Discord with Spectrum

Author: selbekk

Diff for: docusaurus/website/core/Footer.js

@@ -47,15 +47,21 @@ class Footer extends React.Component {
           <div>
             <h5>Community</h5>
             <a
-              href="http://stackoverflow.com/questions/tagged/"
+              href="https://stackoverflow.com/questions/tagged/create-react-app"
               target="_blank"
               rel="noreferrer noopener"
             >
               Stack Overflow
             </a>
-            <a href="https://discordapp.com/">Project Chat</a>
+            <a 
+              href="https://spectrum.chat/react" 
+              target="_blank"
+              rel="noreferrer noopener"
+            >
+              Spectrum
+            </a>
             <a
-              href="https://twitter.com/"
+              href="https://twitter.com/reactjs"
               target="_blank"
               rel="noreferrer noopener"
             >
@@ -64,12 +70,12 @@ class Footer extends React.Component {
           </div>
           <div>
             <h5>More</h5>
-            <a href="https://github.com/">GitHub</a>
+            <a href="https://www.github.com/facebook/create-react-app">GitHub</a>
             <a
               className="github-button"
               href={this.props.config.repoUrl}
               data-icon="octicon-star"
-              data-count-href="/facebook/docusaurus/stargazers"
+              data-count-href="/facebook/create-react-app/stargazers"
               data-show-count="true"
               data-count-aria-label="# stargazers on GitHub"
               aria-label="Star this project on GitHub"

Diff for: docusaurus/website/siteConfig.js

@@ -28,6 +28,7 @@ const siteConfig = {
   headerLinks: [
     { doc: 'getting-started', label: 'Getting started' },
     { href: 'https://reactjs.org/community/support.html', label: 'Help' },
+    { href: 'https://www.github.com/facebook/create-react-app', label: 'GitHub' },
   ],
 
   /* path to images for header/footer */
@@ -77,7 +78,7 @@ const siteConfig = {
 
   // You may provide arbitrary config keys to be used as needed by your
   // template. For example, if you need your repo's URL...
-  //   repoUrl: 'https://github.com/facebook/test-site',
+  repoUrl: 'https://github.com/facebook/create-react-app',
 };
 
 module.exports = siteConfig;