Documentation for template alarm_control_panel (#9801)

* Added new platform documentation

* Move documentation to new integrations location

* Update documentation to modern level

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

source/_integrations/alarm_control_panel.template.markdown

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+---
+title: "Template Alarm Control Panel"
+description: "Instructions on how to integrate Template Alarm Control Panels into Home Assistant."
+ha_category: 
+  - Alarm
+ha_release: 0.105
+ha_iot_class: "Local Push"
+logo: home-assistant.png
+ha_qa_scale: internal
+---
+
+The `template` integrations creates alarm control panels that combine integrations or adds pre-processing logic to actions.
+
+There are several powerful ways to use this integration, including grouping existing integrations into a simpler integrations, or adding logic that Home Assistant will execute when accessed.
+
+For example, if you want to expose a true alarm panel to Google Home, Alexa, or Homekit - but limit its ability to disarm when there's no one home, you can do that using a template.
+
+Another use case could be grouping a series of internal and external locks together to represent "Home" and "Away" lock states.
+
+This can simplify the GUI and make it easier to write automations.
+
+In optimistic mode, the alarm control panel will immediately change state after every command. Otherwise, the lock will wait for state confirmation from the template. Try to enable it, if experiencing incorrect lock operation.
+
+## Configuration
+
+To enable a Template Alarm Control Panel in your installation, add the following to your `configuration.yaml` file:
+
+{% raw %}
+
+```yaml
+# Example configuration.yaml entry
+alarm_control_panel:
+  - platform: template
+    name: Safe Alarm Panel
+    value_template: "{{ states('alarm_control_panel.real_alarm') }}"
+    arm_away:
+      service: alarm_control_panel.alarm_arm_away
+      data:
+        entity_id: alarm_control_panel.real_alarm
+        code: !secret alarm_code
+    arm_home:
+      service: alarm_control_panel.alarm_arm_home
+      data:
+        entity_id: alarm_control_panel.real_alarm
+        code: !secret alarm_code
+    disarm:
+      - condition: state
+        entity_id: device_tracker.paulus
+        state: 'home'
+      - service: alarm_control_panel.alarm_arm_home
+        data:
+          entity_id: alarm_control_panel.real_alarm
+          code: !secret alarm_code
+```
+
+{% endraw %}
+
+{% configuration %}
+  name:
+    description: Name to use in the frontend.
+    required: false
+    type: string
+    default: Template Alarm Control Panel
+  value_template:
+    description: Defines a template to set the state of the alarm panel.
+    required: false
+    type: template
+  disarm:
+    description: Defines an action to run when the alarm is disarmed.
+    required: false
+    type: action
+  arm_away:
+    description: Defines an action to run when the alarm is armed to away mode.
+    required: false
+    type: action
+  arm_home:
+    description: Defines an action to run when the alarm is armed to home mode.
+    required: false
+    type: action
+  arm_night:
+    description: Defines an action to run when the alarm is armed to night mode.
+    required: false
+    type: action
+{% endconfiguration %}
+
+## Considerations
+
+If you are using the state of a integration that takes extra time to load, the Template Alarm Control Panel may get an `unknown` state during startup. This results in error messages in your log file until that integration has completed loading. If you use `is_state()` function in your template, you can avoid this situation.
+
+For example, you would replace {% raw %}`{{ states.switch.source.state == 'on' }}`{% endraw %} with this equivalent that returns `true`/`false` and never gives an unknown result: {% raw %}`{{ is_state('switch.source', 'on') }}`{% endraw %}