Add MQTT select subentry support

Author: jbouwh

source/_integrations/mqtt.markdown

@@ -133,6 +133,7 @@ MQTT Devices and entities can be set up through [MQTT -discovery](#mqtt-discover
 - [Lock](/integrations/lock.mqtt/)
 - [Notify](/integrations/notify.mqtt/)
 - [Number](/integrations/number.mqtt/)
+- [Select](/integrations/select.mqtt/)
 - [Sensor](/integrations/sensor.mqtt/)
 - [Switch](/integrations/switch.mqtt/)
 

source/_integrations/select.mqtt.markdown

@@ -12,7 +12,7 @@ The `mqtt` Select platform allows you to integrate devices that might expose con
 
 ## Configuration
 
-To use an MQTT select entity in your installation, add the following to your {% term "`configuration.yaml`" %} file.
+To use an MQTT select entity in your installation, [add a MQTT device as a subentry](/integrations/mqtt/#configuration), or add the following to your {% term "`configuration.yaml`" %} file.
 {% include integrations/restart_ha_after_config_inclusion.md %}
 
 ```yaml