Remove dead link

The project seems died. The link leads to porno.

docs/index.html

@@ -148,35 +148,6 @@ <h4>Mozilla Webmaker</h4>
       </div>
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-    <div class="user">
-      <h4>Backbeam</h4>
-
-      <div class="col-sm-6">
-        <blockquote>
-          <p>
-            &ldquo;Backbeam provides tools for mobile and web
-            development. When we were planning the web developing
-            features we needed an easy-to-use yet powerful
-            templating engine. But almost all JavaScript
-            templating engines lacked of important features such
-            as template inheritance or flexibility to add custom
-            behaviours (e.g. custom filters). Then we just saw the
-            announcement of nunjucks on James' website. Since that
-            moment we knew that nunjucks would be THE choice. Now
-            we use nunjucks in many parts of our product. Users
-            can edit HTML and email templates using nunjucks right
-            in their browsers. We are really happy with our choice
-            :)&rdquo;
-          </p>
-
-          <p>&ndash; Alberto Gimeno, founder of <a href="http://backbeam.io/">backbeam.io</a></p>
-        </blockquote>
-      </div>
-      <div class="col-sm-6">
-        <a href="img/backbeam2x.png"><img src="img/backbeam2x.png" /></a>
-      </div>
-    </div>
-
     <div class="user">
       <h4>Apostrophe CMS</h4>
       <div class="col-sm-6">