Add flash and transition feature flags for MQTT json light (#38478)

source/_integrations/light.mqtt.markdown

@@ -666,6 +666,11 @@ effect_list:
   description: The list of effects the light supports.
   required: false
   type: [string, list]
+flash:
+  description: Flag that defines if light supports the flash feature.
+  required: false
+  type: boolean
+  default: true
 flash_time_long:
   description: The duration, in seconds, of a “long” flash.
   required: false
@@ -757,6 +762,11 @@ supported_color_modes:
   description: A list of color modes supported by the list. Possible color modes are `onoff`, `brightness`, `color_temp`, `hs`, `xy`, `rgb`, `rgbw`, `rgbww`, `white`. Note that if `onoff` **or** `brightness` are used, that must be the _only_ value in the list.
   required: false
   type: list
+transition:
+  description: Flag that defines if light supports the transition feature.
+  required: false
+  type: boolean
+  default: true
 unique_id:
    description: An ID that uniquely identifies this light. If two lights have the same unique ID, Home Assistant will raise an exception. Required when used with device-based discovery.
    required: false

source/_integrations/mqtt.markdown

@@ -740,6 +740,7 @@ support_url:
     'evt_typ':             'event_types',
     'exp_aft':             'expire_after',
     'fanspd_lst':          'fan_speed_list',
+    'flsh':                'flash',
     'flsh_tlng':           'flash_time_long',
     'flsh_tsht':           'flash_time_short',
     'fx_cmd_t':            'effect_command_topic',
@@ -933,6 +934,7 @@ support_url:
     'tilt_status_t':       'tilt_status_topic',
     'tilt_status_tpl':     'tilt_status_template',
     'tit':                 'title',
+    'trns':                'transition',
     'uniq_id':             'unique_id',
     'unit_of_meas':        'unit_of_measurement',
     'url_t':               'url_topic',