Add suggested_display_precision config setting for MQTT sensor (#26064)

* Add precision config setting to MQTT sensor

* rename to suggested_display_precision

source/_integrations/mqtt.markdown

@@ -441,6 +441,7 @@ Configuration variable names in the discovery payload may be abbreviated to cons
     'stat_val_tpl':        'state_value_template',
     'step':                'step',
     'stype':               'subtype',
+    'sug_dsp_prc':         'suggested_display_precision',
     'sup_clrm':            'supported_color_modes',
     'sup_dur':             'support_duration',
     'sup_vol':             'support_volume_set',

source/_integrations/sensor.mqtt.markdown

@@ -170,6 +170,10 @@ payload_not_available:
   required: false
   type: string
   default: offline
+suggested_display_precision:
+  description: The number of decimals which should be used in the sensor's state after rounding.
+  required: false
+  type: integer
 qos:
   description: The maximum QoS level of the state topic.
   required: false
@@ -323,6 +327,7 @@ mqtt:
   sensor:
     - name: "Temperature"
       state_topic: "office/sensor1"
+      suggested_display_precision: 1
       unit_of_measurement: "°C"
       value_template: "{{ value_json.temperature }}"
     - name: "Humidity"