initial documentation for aftership sensor (home-assistant#7616)

* initial documentation for aftership sensor

* ✏️ Tweaks

* Minor changes

source/_components/sensor.aftership.markdown

@@ -0,0 +1,52 @@
+---
+layout: page
+title: AfterShip Sensor
+description: "Instructions on how to set up AfterShip sensors within Home Assistant."
+date: 2018-11-24 01:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: aftership.png
+ha_category: Postal Service
+ha_release: 0.85
+ha_iot_class: "Cloud Polling"
+---
+
+The `aftership` platform allows one to track deliveries by [AfterShip](https://www.aftership.com), a service that supports 490+ couriers worldwide. It is free to use up to 100 tracked packages per month, after that there is a fee.
+
+The sensor value shows the number of packages that are not in `Delivered` state. As attributes are the number of packages per status.
+
+## {% linkable_title Setup %}
+
+To use this sensor, you need an [AfterShip Account](https://accounts.aftership.com/register) and set up an API Key. To set up an API Key go to [AfterShip API](https://secure.aftership.com/#/settings/api) page, and copy existing key or generate a new one.
+
+<p class='note info'>
+AfterShip recently started requiring having a credit card on file even if you are only using the free plan. That does not change the functionality of the platform, just something to be aware of.
+</p>
+
+## {% linkable_title Configuration %}
+
+To enable this sensor, add the following lines to your `configuration.yaml`:
+
+```yaml
+sensor:
+  - platform: aftership
+    api_key: AFTERSHIP_APIKEY
+```
+
+{% configuration %}
+name:
+  description: The sensor name to use in the frontend.
+  required: false
+  default: "aftership"
+  type: string
+api_key:
+  description: The API key for AfterShip.
+  required: true
+  type: string
+{% endconfiguration %}
+
+<p class='note info'>
+This component retrieves data from AfterShip public REST API, but the component is not affiliated with AfterShip.
+</p>