Minor README clarifications.

README.md

@@ -66,11 +66,12 @@ echo 00:00:0a:bb:28:fc | nc -N host.docker.internal 18888
 
 This example uses the OpenBSD netcat variant to send a TCP packet containing
 the requested MAC address to wake. The packet is sent to port 18888 on the
-host.
+host, where this container should be listening.
 
-For this to work, you may need to configure your client container to support
-the special `host.docker.internal` host. E.g., `docker run --add-host
-host.docker.internal:host-gateway ...`. Or, with Docker Compose:
+For this to work, you may need to configure your client container (the one
+running the `echo` command) to support the special `host.docker.internal`
+host. E.g., `docker run --add-host host.docker.internal:host-gateway ...`. Or,
+with Docker Compose:
 
 ```yaml
 extra_hosts: