Persistent_notification service description (#2407)

* Persistent_notification service description

* Add service name to services.yaml

homeassistant/components/persistent_notification.py

@@ -4,6 +4,7 @@ A component which is collecting configuration errors.
 For more details about this component, please refer to the documentation at
 https://home-assistant.io/components/persistent_notification/
 """
+import os
 import logging
 
 import voluptuous as vol
@@ -12,6 +13,7 @@ from homeassistant.exceptions import TemplateError
 from homeassistant.helpers import template, config_validation as cv
 from homeassistant.helpers.entity import generate_entity_id
 from homeassistant.util import slugify
+from homeassistant.config import load_yaml_config_file
 
 DOMAIN = 'persistent_notification'
 ENTITY_ID_FORMAT = DOMAIN + '.{}'
@@ -74,7 +76,10 @@ def setup(hass, config):
 
         hass.states.set(entity_id, message, attr)
 
-    hass.services.register(DOMAIN, SERVICE_CREATE, create_service, {},
+    descriptions = load_yaml_config_file(
+        os.path.join(os.path.dirname(__file__), 'services.yaml'))
+    hass.services.register(DOMAIN, SERVICE_CREATE, create_service,
+                           descriptions[DOMAIN][SERVICE_CREATE],
                            SCHEMA_SERVICE_CREATE)
 
     return True

homeassistant/components/services.yaml

@@ -0,0 +1,16 @@
+persistent_notification:
+  create:
+    description: Show a notification in the frontend
+
+    fields:
+      message:
+        description: Message body of the notification. [Templates accepted]
+        example: Please check your configuration.yaml.
+
+      title:
+        description: Optional title for your notification. [Optional, Templates accepted]
+        example: Test notification
+
+      notification_id:
+        description: Target ID of the notification, will replace a notification with the same Id. [Optional]
+        example: 1234