diff --git a/doc/example.env b/doc/example.env
index 303a25e6..6696a4eb 100644
--- a/doc/example.env
+++ b/doc/example.env
@@ -10,6 +10,10 @@ BUILD_INFO=latest
 # otherwise the port specified here will be publicly accessible
 PORT=8080
 
+# Uncomment PORT_SERVER variable if you did the same in docker-compose.yml
+# to make embeds work.
+# PORT_SERVER=8081
+
 # How many waitress threads to start
 # 4 is the default amount of threads. If you experience performance
 # degradation with a large number of posts, increasing this may