Remove blog content from website

Summary:
- Remove long-outdated blog article from website (`/blog` was previously removed from nav) — we will use the React Native blog for future posts!
- Replace blog link on Help page ("Stay up to date") with link to releases.
- Remove unused `i18n/en.json` file.

Reviewed By: jacdebug

Differential Revision: D42536010

fbshipit-source-id: 750098ec14c708338e622cb11ea5c48bcd7b79b9

website/src/pages/help/index.js

@@ -68,7 +68,11 @@ const supportLinks = [
           Twitter.
         </li>
         <li>
-          Subscribe to the <a href="/metro/blog/">Metro blog</a>.
+          Browse our{' '}
+          <a href="https://github.com/facebook/metro/releases">
+            latest releases on GitHub
+          </a>
+          .
         </li>
       </ul>
     ),