Fix nil vs false values for defaults

docs/plugin-doc.html.erb

@@ -84,7 +84,7 @@ This is what it might look like in your config file:
 <% elsif config[:validate].is_a?(Array) -%>
   <li> Value can be any of: <%= config[:validate].map(&:inspect).join(", ") %> </li>
 <% end -%>
-<% if config[:default] -%>
+<% if config[:default].nil? -%>
   <li> Default value is <%= config[:default].inspect %> </li>
 <% else -%>
   <li> There is no default value for this setting. </li>