Readme update for nginx proxy

readme.md

@@ -121,8 +121,9 @@ http {
         server  127.0.0.1:8083;
     }
     server {
+            client_max_body_size 20M;
             location /calibre {
-                proxy_bind              $server_addr;
+                proxy_bind              http://calibre;
                 proxy_pass              http://127.0.0.1:8083;
                 proxy_set_header        Host            $http_host;
                 proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
@@ -132,6 +133,10 @@ http {
     }
 }
 ```
+*Note: If using SSL in your reverse proxy on a non-standard port, the following proxy_redirect line may be required:*
+```
+proxy_redirect http://$host/ https://$host:12345/;
+```
 
 Apache 2.4 configuration for a local server listening on port 443, mapping calibre web to /calibre-web: