Handle underscores in markdown output too

lib/01-menu.rb

@@ -26,7 +26,7 @@ module MenuTextHelper
         p = "#{site_url}#{path.join('/')}/#{a}"
         i = @items[%r{.*#{p}}]
 
-        out.concat("#{'  ' * depth}- [#{i[:title] || a.gsub('.md', '').split('-').map(&:capitalize).join(' ')}](#{i[:path]})\n")
+        out.concat("#{'  ' * depth}- [#{i[:title] || a.gsub('.md', '').gsub('_', '-').split('-').map(&:capitalize).join(' ')}](#{i[:path]})\n")
       else
         # Prettify directory name (replace - with spaces and capitalise words)
         d = a[:data].split('-').map(&:capitalize).join(' ')