Marked install with npm as "recommended"

index.html

@@ -177,7 +177,7 @@
                         Vis.js runs fine on Chrome, Firefox, Opera, Safari, IE9+, and most mobile browsers (with full touch support).
                         This site contains documentation, downloads and live examples of vis.js. The <a href="https://github.com/almende/vis/issues">sourcecode of vis.js</a> is available at Github. For questions, issues, and suggestions please use the <a href="https://github.com/almende/vis/issues">issues section</a> of the Github project.
                     </p>
-                    <h3>install with npm</h3>
+                    <h3>install with npm (recommended)</h3>
                     <pre class="prettyprint">npm install vis</pre>
                     <h3>install with bower</h3>
                     <pre class="prettyprint">bower install vis</pre>