Fix a typo.

core/nginx/conf/nginx.conf

@@ -231,7 +231,7 @@ http {
         auth_request /internal/auth/admin;
         proxy_set_header X-Real-IP "";
         proxy_set_header X-Forwarded-For "";
-        proxe_set_header X-Forwarded-By: "";
+        proxy_set_header X-Forwarded-By: "";
         proxy_pass http://$antispam;
         error_page 403 @sso_login;
       }