Add Farabi to real-world uses

doc/realworld.html

@@ -36,6 +36,7 @@
       <li><a href="http://elm-lang.org/Examples.elm">Elm language examples</a></li>
       <li><a href="http://eloquentjavascript.net/chapter1.html">Eloquent JavaScript</a> (book)</li>
       <li><a href="http://www.fastfig.com/">Fastfig</a> (online computation/math tool)</li>
+      <li><a href="https://metacpan.org/module/Farabi">Farabi</a> (Perl editor)</li>
       <li><a href="http://blog.pamelafox.org/2012/02/interactive-html5-slides-with-fathomjs.html">FathomJS integration</a> (slides with editors, again)</li>
       <li><a href="http://tour.golang.org">Go language tour</a></li>
       <li><a href="https://github.com/github/android">GitHub's Android app</a></li>