Update alarm_control_panel.mqtt.markdown (#12291)

* Update alarm_control_panel.mqtt.markdown

Adds missing states:
Complements: https://github.com/home-assistant/core/pull/32541

* payload_arm_custom_bypass added

* MQTT Abbreviation for payload_arm_custom_bypass

MQTT Abbreviation for payload_arm_custom_bypass -> pl_arm_custom_b

Co-authored-by: Franck Nijhof <git@frenck.dev>

source/_docs/mqtt/discovery.markdown

@@ -155,6 +155,7 @@ Supported abbreviations:
     'pl':                  'payload',
     'pl_arm_away':         'payload_arm_away',
     'pl_arm_home':         'payload_arm_home',
+    'pl_arm_custom_b':     'payload_arm_custom_bypass',
     'pl_arm_nite':         'payload_arm_night',
     'pl_avail':            'payload_available',
     'pl_cln_sp':           'payload_clean_spot',

source/_integrations/alarm_control_panel.mqtt.markdown

@@ -16,8 +16,11 @@ The integration will accept the following states from your Alarm Panel (in lower
 - `armed_home`
 - `armed_away`
 - `armed_night`
+- `armed_custom_bypass`
 - `pending`
 - `triggered`
+- `arming`
+- `disarming`
 
 The integration can control your Alarm Panel by publishing to the `command_topic` when a user interacts with the Home Assistant frontend.
 
@@ -118,6 +121,11 @@ payload_arm_night:
   required: false
   type: string
   default: ARM_NIGHT
+payload_arm_custom_bypass:
+  description: The payload to set armed-custom-bypass mode on your Alarm Panel.
+  required: false
+  type: string
+  default: ARM_CUSTOM_BYPASS
 payload_available:
   description: The payload that represents the available state.
   required: false