[ZEPPELIN-5830] Security page header styling (#4516)

When creating #4478 I ran into trouble running jekyll so I couldn't test the output.

I have since tested the output and made some updates accordingly.
diff --git a/assets/themes/zeppelin/css/style.css b/assets/themes/zeppelin/css/style.css
index f70c339..2e985b7 100644
--- a/assets/themes/zeppelin/css/style.css
+++ b/assets/themes/zeppelin/css/style.css
@@ -1117,6 +1117,10 @@
     font-size: 15px;
   }
 
+  .docs .dropdown-menu li.title a {
+    color: white !important;
+  }
+
   .navbar-collapse.in {
     overflow-y: auto;
   }
@@ -1214,6 +1218,10 @@
     font-size: 15px;
   }
 
+  .docs .dropdown-menu li.title a {
+    color: white !important;
+  }
+
   .navbar-inverse .navbar-nav > li > a {
     margin-left: -12px;
     font-size: 15px;
@@ -1300,6 +1308,11 @@
   padding-left: 30px;
 }
 
+.docs .dropdown-menu li.title a {
+  padding-left: 0px;
+  color: #3071a9;
+}
+
 /*
 ** Media Queries CSS
 */
diff --git a/security.md b/security.md
index 912b08e..aaea32b 100644
--- a/security.md
+++ b/security.md
@@ -1,3 +1,24 @@
+---
+layout: page
+title: "Security"
+description: "This page explains what security characteristics can be expected from Zeppelin, what measures operators of a Zeppelin instance will have to take, and how to report any security issues found in the Zeppelin software."
+group:
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+{% include JB/setup %}
+
 # Zeppelin Security
 
 This page explains what security characteristics can be expected from