Added documentation for the ELV PCA 301 smart emeter switch (#8717)

* added PCA 301 docu

* added reference to hexfile for jeelink clone

* cosmetics

* typo

* cosmetics; version bump

* added name conf; deleted linebreak

* ✏️ Tweaks

source/_components/switch.pca.markdown

@@ -0,0 +1,40 @@
+---
+layout: page
+title: "ELV PCA 301 Switch"
+description: "Instructions on how to integrate ELV PCA 301 switches into Home Assistant."
+date: 2019-02-24 18:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: elv.png
+ha_category: Switch
+ha_iot_class: Local Polling
+ha_release: 0.95
+---
+
+The `pca` switch platform allows you to control the state of your [ELV PCA 301 smart switch](https://www.elv.de/funkschaltsteckdose-fuer-energiekostenmonitor-pca-301.html). You need an 868 MHz interface like the [JeeLink](https://www.digitalsmarties.net/products/jeelink) flashed with the [pca-hex firmware](https://github.com/mhop/fhem-mirror/blob/master/fhem/FHEM/firmware/JeeLink_PCA301.hex).
+
+## {% linkable_title Configuration %}
+
+To use your PCA 301 switch or socket in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+switch:
+  - platform: pca
+    device: SERIAL_PORT
+```
+
+This platform will add all PCA 301 switches which are in range. You can read the total used energy in KWh and the current power in Watt.
+
+{% configuration %}
+device:
+  description: "The path to you serial console. Get it via: `ls /dev/tty*`."
+  required: true
+  type: string
+name: 
+  description: Default name for the plugs.
+  required: false
+  type: string
+{% endconfiguration %}