consistent description in readme file

README.md

@@ -17,9 +17,7 @@
 - Communication over TCP and/or websocket, including support for SSL/TLS
 - Support QoS 0, QoS 1 and QoS 2 messages flow
 - Client auto-reconnection on network lost
-- Functionality expansion; plugins included:
-  - Authentication through password file
-  - Basic `$SYS` topics
+- Functionality expansion; plugins included: authentication and `$SYS` topic publishing
 
 ## Installation