Axis documentation (#2549)

* First draft of Axis component documentation

* Small improvements

* Added information about lowest supported Axis firmware

* Trigger time better explains functionality than scan interval

* Simplified explanation of automatic discovery

* Rephrasing manually configuring device

* Keep first and second level variables separated for ease of reading

* Moved up dependency and used Hassbian paths as an example

* Indented include variables descriptions to clarify their relation

* Made configuration variables tile linkable

* Axis devices are part of the discovery mechanism

* Update axis.markdown

* Update binary_sensor.axis.markdown

* Update camera.axis.markdown

source/_components/binary_sensor.axis.markdown

@@ -0,0 +1,28 @@
+---
+layout: page
+title: "Axis Binary Sensor"
+description: "Instructions how to integrate Axis binary sensors into Home Assistant."
+date: 2017-04-01 19:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: axis.png
+ha_category: Binary Sensor
+ha_iot_class: "Local Push"
+ha_release: "0.45"
+---
+
+The `Axis` platform allows you to get data from your [Axis](https://www.axis.com/) devices from within Home Assistant.
+
+See the [Axis main component](/components/axis/) for configuration instructions.
+
+The following sensor types are supported:
+
+
+ * Motion detection
+ * Passive IR motion detection
+ * Sound detection
+ * Day/night mode
+ * Tampering detection
+ * Input port