Add blog post about configuration URL and entity categories (#1108)

Co-authored-by: Franck Nijhof <git@frenck.dev>
Co-authored-by: Joakim Sørensen <joasoe@gmail.com>

blog/2021-10-26-config-entity.md

@@ -0,0 +1,35 @@
+---
+author: Erik Montnémery
+authorURL: https://github.com/emontnemery
+title: "Device configuration URL and entity categories"
+---
+
+Home Assistant Core 2021.11 introduces two new concepts to make managing devices easier,
+device configuration URL and entity categories.
+
+### Device configuration URL
+
+It's now possible to provide a configuration_url as part of the device registry information.
+The configuration_url is used in the device card to allow the user to visit the device
+for configuration or diagnostics which is not available in Home Assistant.
+Note that the URL linked to is not proxied by Home Assistant, so this typically won't work
+when connecting to Home Assistant remotely.
+
+[![Screenshot showing visit device](/img/en/blog/2021-10-26-config-entity/configuration_url.png)](/img/en/blog/2021-10-26-config-entity/configuration_url.png)
+
+### Entity categories 
+
+Entities now have an optional property `entity_category` for classifying non-primary
+entities. Set to `config` for entities that allow changing the configuration of a device,
+for example, a switching entity making it possible to turn the background illumination of a
+switch on and off. Set to `diagnostic` for an entity exposing some configuration parameter
+or diagnostics of a device but does not allow changing it, for example, a sensor showing
+RSSI or MAC address with allowed values.
+
+Entities which have the `entity_category` set:
+- Are not included in a service call targetting a whole device or area.
+- Are, by default, not exposed to Google Assistant or Alexa.
+- Are shown on a separate card on the device configuration page.
+- Do not show up on the automatically generated Lovelace Dashboards.
+
+[![Screenshot showing seperation of entity categories](/img/en/blog/2021-10-26-config-entity/entity_categories.png)](/img/en/blog/2021-10-26-config-entity/entity_categories.png)