Add initial docs for cloud component

source/_components/cloud.markdown

@@ -0,0 +1,66 @@
+---
+layout: page
+title: "Cloud"
+description: "Enable the Home Assistant Cloud integration."
+date: 2017-11-17 20:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: home-assistant.png
+ha_release: 0.57
+---
+
+The Home Assistant Cloud allows you to quickly integrate your local instance with various cloud services. Any processing of services from other cloud services is handled by your local instance.
+
+To get started, create an account and log in via the configuration panel in your Home Assistant instance. There is no need to configure your router or expose your instance to the internet in any other way.
+
+### {% linkable_title Amazon Alexa %}
+
+The Alexa integration allows users to control the entities via the [Home Assistant Smart Home skill for Alexa][alexa skill]. This means that you can say things like "Alexa, turn on the kitchen light" to control your local instance.
+
+```yaml
+# Example configuration.yaml entry configuring Alexa
+cloud:
+  alexa:
+    filter:
+      include_entities:
+        - light.kitchen
+      include_domains:
+        - switch
+      exclude_entities:
+        - light.living_room
+      exclude_domains:
+        - script
+```
+
+{% configuration %}
+alexa:
+  description: Configuration options for the Amazon Alexa integration.
+  required: false
+  type: map
+  keys:
+    filter:
+      description: Filters for entities to include/exclude from Alexa.
+      required: false
+      type: map
+      keys:
+        include_entities:
+          description: Entity IDs to include.
+          required: false
+          type: list
+        include_domains:
+          description: Domains to include.
+          required: false
+          type: list
+        exclude_entities:
+          description: Entity IDs to exclude.
+          required: false
+          type: list
+        exclude_domains:
+          description: Domains to exclude.
+          required: false
+          type: list
+{% endconfiguration %}
+
+[alexa skill]: https://alexa.amazon.com/spa/index.html#skills/dp/B0772J1QKB/?ref=skill_dsk_skb_sr_2