Apply overline after rendering for compatibility with jekyll-figure

_source/_plugins/overline.rb

@@ -5,9 +5,9 @@ module Jekyll
     end
   end
 
-  Hooks.register [:documents, :pages], :pre_render do |item|
+  Hooks.register [:documents, :pages], :post_render do |item|
     if item.output_ext == ".html"
-      item.content = OverlineFilter.apply_overline(item.content)
+      item.output = OverlineFilter.apply_overline(item.output)
     end
   end
 end