Update connection-settings.md default broker listener port (#777)

#775 but from a branch instead of a fork

Co-authored-by: Alain Uyidi <[email protected]>

Author: timtay-microsoft

doc/reference/connection-settings.md

@@ -13,7 +13,7 @@ The MqttConnectionSettings class enables the operator to configure the MQTT Conn
 |Name|Environment variable|Required|Type|Default value|Description|
 |-|-|-|-|-|-|
 |`Hostname`|`AIO_BROKER_HOSTNAME`|yes|string|n/a|FQDN to the endpoint, eg: mybroker.mydomain.com|
-|`TcpPort`|`AIO_BROKER_TCP_PORT`|no|uint16|`8883`|TCP port to access the endpoint eg: 8883|
+|`TcpPort`|`AIO_BROKER_TCP_PORT`|no|uint16|`18883`|TCP port to access the endpoint eg: 18883|
 |`UseTls`|`AIO_MQTT_USE_TLS`|no|bool|`true`|Enable TLS negotiation (disabling not recommended for production)|
 |`CaFile`|`AIO_TLS_CA_FILE`|no|string|null|Path to a PEM file to validate server identity|
 |`CleanStart`|`AIO_MQTT_CLEAN_START`|no|bool|false|Whether to use persistent session on first connect, subsequent connections will be `false`. `true` requires a unique `ClientId`.