Add documentation for Srp Energy (#7289)

* Add documentation for Srp Energy

* Fix typo. Add standard configuration section.

source/_components/sensor.srpenergy.markdown

@@ -0,0 +1,45 @@
+---
+layout: page
+title: "SRP Energy Sensor"
+description: "How to integrate SRP Energy within Home Assistant."
+date: 2018-10-30 08:00
+sidebar: true
+comments: false
+ha_category: Energy
+ha_release: "0.83"
+ha_iot_class: "Cloud Polling"
+---
+
+The `srp_energy` component shows information from Srp hourly energy usage report for their customers. The srpenergy module fetches the data found on the website.
+
+You need a Username, Password, and AccountId which you can create at [Srp](https://www.srpnet.com).
+
+## {% linkable_title Configuration %}
+
+To add Srp Energy to your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: srp_energy
+    username: YOUR_USERNAME
+    password: YOUR_PASSWORD
+    id: YOUR_ACCOUNT_ID
+```
+
+{% configuration %}
+username:
+  description: Your username for SRP.
+  required: true
+  type: string
+password:
+  description: Your password for SRP.
+  required: true
+  type: string
+id:
+  description: Your account id for SRP.
+  required: true
+  type: string
+{% endconfiguration %}
+
+Details about the API are available in the [SRP Energy Developers API documentation](https://srpenergy-api-client-python.readthedocs.io/en/latest/?badge=latest).