added header

Author: Pavan Krishna Nimmagadda

docs-layout/source/layouts/_header.erb

@@ -35,7 +35,7 @@
   <% if current_page.data.title %> <%# this is a proxy for if !homepage %>
     <header class="header header-layout">
       <h1 class="logo">
-        <a href="/"><%= vars.book_title || 'Default Book Title' %></a>
+        <a href="/"><%= vars.book_title || 'Appdynamics' %></a>
       </h1>
       <%= yield_for_archive_drop_down_menu %>
       <%# @TODO: Replace with dynamic versioning %>