Add entity registry docs

source/_docs/configuration/entity-registry.markdown

@@ -0,0 +1,54 @@
+---
+layout: page
+title: "Entity Registry"
+description: "The entity registry contains."
+date: 2016-04-20 06:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+---
+
+<p class='note'>
+This is a new and experimental feature of Home Assistant.
+</p>
+
+Starting with version 0.63, Home Assistant keeps a registry of known entities.
+The entity registry makes sure that entities get unique identifiers and allow
+customizing the identifiers and names of these entities.
+
+As this is still a very new part of Home Assistant, changes will require a
+restart of Home Assistant to take affect. A config user interface will be added
+in a future version.
+
+<p class='note'>
+An entity needs to have a unique ID to be registered in the entity registry.
+Not all integrations currently provide a unique id for their entities.
+</p>
+
+The entity registry is stored in `<config>/entity_registry.yaml`. As a user,
+you are unable to add entries, only update them. Here is an example file:
+
+```
+climate.downstairs_virtual:
+  platform: nest
+  unique_id: EPoMyWkpNyoYu3pGlmGxabcdefghijkl
+  name: Downstairs thermostat
+light.study_ceiling:
+  platform: hue
+  unique_id: f0:fe:6b:00:14:00:00:00-00
+  disabled_by: user
+```
+
+As a user, you can change the `entity_id` and add the `name` and `disabled_by`
+value to each entry.
+
+ - The value of `name` will override the name of the entity as given by the
+   integration.
+
+   _Added in Home Assistant 0.64._
+ - The key `disabled_by` can either be `hass` or `user`. This functionality
+   is even more experimental than the whole entity registry itself and might
+   cause integrations to fail and might be removed in the future.
+
+   _Added in Home Assistant 0.64._

source/_includes/asides/docs_navigation.html

@@ -3,7 +3,7 @@
     <h1 class="title delta">Topics</h1>
     <ul class='divided sidebar-menu'>
       <li>
-        <b>{% active_link /faq/ FAQ %}</b> | 
+        <b>{% active_link /faq/ FAQ %}</b> |
         <b>{% active_link /docs/glossary/ Glossary %}</b>
       </li>
       <li>
@@ -23,6 +23,7 @@
           <li>{% active_link /docs/configuration/yaml/ YAML %}</li>
           <li>{% active_link /docs/configuration/basic/ Basic information %}</li>
           <li>{% active_link /docs/configuration/devices/ Setting up devices %}</li>
+          <li>{% active_link /docs/configuration/entity-registry/ Entity Registry %}</li>
           <li>{% active_link /docs/configuration/customizing-devices/ Customizing entities %}</li>
           <li>{% active_link /docs/configuration/troubleshooting/ Troubleshooting %}</li>
           <li>{% active_link /docs/configuration/securing/ Security Check Points %}</li>