updated docs

README.md

@@ -30,6 +30,7 @@ services:
 ```
 
 This is the configuration (mosquitto.conf):
+
 ```
 listener 8883
 certfile /data/live/domain/cert.pem
@@ -47,7 +48,14 @@ psk_file /etc/mosquitto/pskfile
 The first port is used with a passwd file, that you can create in the usual way.
 
 You also need to create a file named "pskfile" to access the "secondary" port, with this syntax:
+
 ```
 user1:password1
 user2:password2
 ```
+
+## password update
+
+```sh
+docker compose exec server mosquitto_passwd -b /etc/mosquitto/passwd username StrongPa$$w0rd
+```