Added documentation for the rpi_pfio platform. (#2597)

* Added documentation for the rpi_pfio platform.

* Changed version to next release

* Removed unused pull mode

source/_components/switch.rpi_pfio.markdown

@@ -0,0 +1,37 @@
+---
+layout: page
+title: "PiFace Digital I/O Switch"
+description: "Instructions how to integrate the PiFace Digital I/O module into Home Assistant as a switch."
+date: 2016-05-08 15:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: raspberry-pi.png
+ha_category: Switch
+ha_release: 0.45
+---
+
+The `rpi_pfio` switch platform allows you to control the [PiFace Digital I/O](https://www.element14.com/community/docs/DOC-69001) module.
+
+To use your PiFace Digital I/O module in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+switch:
+  - platform: rpi_pfio
+    ports:
+      0:
+        name: Doorlock
+        invert_logic: true
+      1:
+        name: Light Desk
+```
+
+Configuration variables:
+
+- **ports** array (*Required*): Array of used ports.
+  - **num** (*Required*): Port number.
+    - **name** (*Required*): Port name.
+    - **invert_logic** (*Optional*): If true, inverts the output logic to ACTIVE LOW. Default is false (ACTIVE HIGH).
+