Improve release script & enable versioning documentation (#1521)

* Add version selection page

* Update the CDN urls in the documentation

* Generate new version and publish documentation in release script

* Update CDN urls when NEXT_VERSION is not provided

* Remove bower-related from release script

* Improve instructions running on the release branch 

and without next version

* Add a suffix to the branch name

* Update CSS stylesheet replacement

* Update release.sh

* Change npm to Yarn

* Fix calling `version` script

* Run `prestart` in `version`

* Wrap `Latest Version` descriptions with p tag

* Explicitly specify files to commit in the website

website/pages/en/versions.js

@@ -0,0 +1,111 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const fs = require('fs');
+const React = require('react');
+
+const {Container} = require('../../core/CompLibrary');
+
+const CWD = process.cwd();
+
+const {title, baseUrl, repoUrl} = require(`${CWD}/siteConfig.js`);
+const versions = fs.existsSync(`${CWD}/versions.json`)
+    ? require(`${CWD}/versions.json`) : [];
+
+function Versions(props) {
+    const latestVersion = versions[0];
+    const language = props.language && props.language !== 'en' ?
+        props.language + '/' : '';
+    return (
+        <div className="docMainWrapper wrapper">
+        <Container className="mainContainer versionsContainer">
+          <div className="post">
+            <header className="postHeader">
+              <h1>{title} Versions</h1>
+            </header>
+            <h3 id="latest">Current version (Stable)</h3>
+            <p>Latest version of KaTeX.</p>
+            <table className="versions">
+              <tbody>
+                <tr>
+                  <th>{latestVersion}</th>
+                  <td>
+                    <a
+                      href={`${baseUrl}docs/${language}node.html`}>
+                      Documentation
+                    </a>
+                  </td>
+                  <td>
+                    <a href={`${repoUrl}/releases/tag/v${latestVersion}`}>
+                      Release Notes
+                    </a>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+            <h3 id="rc">Latest Version</h3>
+            <p>
+              Here you can find the latest documentation and unreleased code.
+            </p>
+            <table className="versions">
+              <tbody>
+                <tr>
+                  <th>master</th>
+                  <td>
+                    <a
+                      href={`${baseUrl}docs/${language}next/node.html`}>
+                      Documentation
+                    </a>
+                  </td>
+                  <td>
+                    <a href={repoUrl}>Source Code</a>
+                  </td>
+                </tr>
+              </tbody>
+            </table>
+            <h3 id="archive">Past Versions</h3>
+            <p>
+              Here you can find documentation for previous versions of KaTeX.
+            </p>
+            <table className="versions">
+              <tbody>
+                {versions.map(
+                  version =>
+                    version !== latestVersion && (
+                      <tr key={version}>
+                        <th>{version}</th>
+                        <td>
+                          <a
+                            href={`${baseUrl}docs/${
+                              language
+                            }${version}/node.html`}>
+                            Documentation
+                          </a>
+                        </td>
+                        <td>
+                          <a href={`${repoUrl}/releases/tag/v${version}`}>
+                            Release Notes
+                          </a>
+                        </td>
+                      </tr>
+                    )
+                )}
+              </tbody>
+            </table>
+            <p>
+              You can find past versions of KaTeX on{' '}
+              <a href={`${repoUrl}/releases`}>GitHub</a>.
+            </p>
+          </div>
+        </Container>
+      </div>
+    );
+}
+
+Versions.title = 'Versions';
+
+module.exports = Versions;