fix: fix broken anchors

Author: filipesilva

public/_includes/_main-nav.jade

@@ -1,7 +1,7 @@
 - var language = current.path[1] || 'ts'
 - if (language !== 'ts' || language !== 'js' || language !== 'dart') { language = 'ts'; }
 
-nav.main-nav.l-pinned-top.l-layer-5
+nav(class="main-nav l-pinned-top l-layer-5", scroll-y-offset-element)
   h1 <a href="/" md-button>Angular <sup>by Google</sup></a>
 
   button(class="main-nav-button main-nav-mobile-trigger l-right" aria-label="View Menu" ng-click="appCtrl.toggleMainMenu($event)" md-button) Site Menu <span class="icon icon-arrow-drop-down"></span>