Restore links in content/inde.md.

src/content/index.md

@@ -20,3 +20,17 @@ visit the [farmOS Community Forum] and read the [Frequently Asked Questions].
 
 You can contribute to the project by [making a donation] or [contributing] in
 other ways.
+
+[Drupal]: https://drupal.org
+[modular]: http://en.wikipedia.org/wiki/Modular_programming
+[extensible]: https://www.drupal.org/download
+[secure]: http://www.drupal.org/documentation/is-drupal-secure
+[farmOS Field Kit]: /guide/app
+[https://farmOS.app]: https://farmOS.app
+[User Guide]: /guide
+[farmOS Community Forum]: https://farmOS.discourse.group
+[making a donation]: /donate
+[contributing]: /community/contribute
+[GNU General Public License]: http://www.gnu.org/copyleft/gpl.html
+[free]: https://en.wikipedia.org/wiki/Free_software
+[open source]: http://en.wikipedia.org/wiki/Open_source