clarify

README.md

@@ -53,7 +53,7 @@ Run `mix phx.server` in repository's root, it will output log into stdout/stderr
 
 ### Using an upstream proxy for federation
 
-Add the following to your `dev.secret.exs` if you want to proxify all http requests that pleroma makes to an upstream proxy server:
+Add the following to your `dev.secret.exs` or `prod.secret.exs` if you want to proxify all http requests that pleroma makes to an upstream proxy server:
 
     config :pleroma, :http,
       proxy_url: "127.0.0.1:8123"