Update sidebar structure

docs/_data/topnav.yml

@@ -5,28 +5,10 @@ topnav:
   items:
     - title: News
       url: /news
+    - title: Download
+      external_url: https://github.com/pmd/pmd/releases/latest
+    - title: Fork us on github
+      external_url: https://github.com/pmd/pmd
 
 #Topnav dropdowns
 topnav_dropdowns:
-- title: Topnav dropdowns
-  folders:
-    - title: Jekyll Resources
-      folderitems:
-        - title: Github Repo
-          external_url: https://github.com/tomjohnson1492/documentation-theme-jekyll
-        - title: Jekyll Talk
-          external_url: https://talk.jekyllrb.com
-        - title: Jekyll documentation
-          external_url: http://jekyllrb.com/docs/home/
-        - title: Jekyll on Stack Overflow
-          external_url: http://stackoverflow.com/questions/tagged/jekyll
-        - title: Jekyll on my blog
-          external_url: http://idratherbewriting.com/category-jekyll/
-    - title: Products
-      folderitems:
-        - title: Jekyll Documentation Theme
-          url: /mydoc_introduction.html
-        - title: Product 1
-          url: /p1_landing_page.html
-        - title: Product 2
-          url: /p2_landing_page.html