Add margin class for jumbotron

Signed-off-by: Eric Poirier <eric.poirier@eclipse-foundation.org>
diff --git a/index.php b/index.php
index 44f50c9..69ae9ae 100644
--- a/index.php
+++ b/index.php
@@ -29,7 +29,7 @@
 
 ob_start();
 ?>
-<div class="jumbotron featured-jumbotron">
+<div class="jumbotron featured-jumbotron margin-bottom-45">
   <div class="container margin-bottom-30">
     <div class="row">
       <div class="col-md-20 col-md-offset-2 col-sm-18 col-sm-offset-3">