Add stub for ACP entity, includes code_format (#18)

* Add stub for ACP entity, includes code_format

* Add key pad info

docs/entity_alarm_control_panel.md

@@ -0,0 +1,25 @@
+---
+title: Alarm Control Panel Entity
+sidebar_label: Alarm Control Panel
+---
+
+> This entry is incomplete. Contribution welcome.
+
+## Properties
+
+> Properties should always only return information from memory and not do I/O (like network requests). Implement `update()` or `async_update()` to fetch data.
+
+| Name | Type | Default | Description
+| ---- | ---- | ------- | -----------
+| code_format | string | `None` | The format of the panel code.
+
+### Available code formats
+
+| Value | Description
+| ----- | -----------
+| None | No code required.
+| Number | Code is a number (Shows ten-key pad on frontend).
+| Any | Code is a string.
+
+## Methods
+

website/sidebars.json

@@ -8,6 +8,7 @@
     ],
     "Entities": [
       "entity_index",
+      "entity_alarm_control_panel",
       "entity_binary_sensor",
       "entity_climate",
       "entity_cover",