Added documentation for the Vilfo Router integration

source/_integrations/vilfo.markdown

@@ -0,0 +1,34 @@
+---
+title: "Vilfo Router"
+description: "Instructions on how to integrate a Vilfo Router into Home Assistant."
+logo: vilfo.png
+ha_release: "0.106"
+ha_category:
+    - Network
+    - System Monitor
+    - Sensor
+ha_iot_class: "Local Polling"
+ha_config_flow: true
+ha_codeowners:
+  - '@ManneW'
+---
+
+The `Vilfo Router` integration allows you to observe the state of your [Vilfo Router](https://www.vilfo.com) from Home Assistant.
+
+It currently supports reporting the current load of the device in percent and the current uptime measured in minutes.
+
+## Configuration
+
+The integration can be added using the UI. Go to **Configuration** >> **Integrations** and click the `+` sign button and select **Vilfo Router** from the list.
+
+To configure the integration you will need the hostname or IP of your router (`admin.vilfo.com` is the default hostname) as well as an API access token.
+
+### Obtaining an access token
+
+The access token for the API can be obtained through the Vilfo web-UI in the pane named "general". Visit [the official API documentation](https://www.vilfo.com/apidocs/#header-authorization) for more information on how to find your token.
+
+<div class="note warning">
+
+In version 1.0.13 of the Vilfo firmware, access tokens are invalidated when a new login to the web UI is made. To prevent web UI logins from interfering with the API calls, you can create a separate user solely for API purposes and use its access token.
+
+</div>