README.md in fluent-plugin-http_shadow-0.0.7 vs README.md in fluent-plugin-http_shadow-0.0.8

@@ -58,9 +58,10 @@
     "blog.ipros.jp": "blog-staging.ipros.jp"
   }
   host_key host
   path_format ${path}
   method_key method
+  protocol_format ${x_forwarded_proto} # default: http
   header_hash { "Referer": "${referer}", "User-Agent": "${user_agent}" }
 </match>
 ```
 
 ## Examples(use cookie)