Add documentation for Smart Meter Texas integration (#14198)

* Add documentation for Smart Meter Texas integration

* Provide better configuration instructions

* Provide better account setup instructions

* Fix mispelling

* Add heading

Co-authored-by: Fabian Affolter <mail@fabian-affolter.ch>

source/_integrations/smart_meter_texas.markdown

@@ -0,0 +1,38 @@
+---
+title: Smart Meter Texas
+description: Instructions on how to integrate Smart Meter Texas into Home Assistant.
+ha_category:
+  - Sensor
+ha_release: 0.115
+ha_iot_class: Cloud Polling
+ha_config_flow: true
+ha_codeowners:
+  - "@grahamwetzler"
+ha_domain: smart_meter_texas
+---
+
+The [Smart Meter Texas](https://www.smartmetertexas.com/) integration allows Texas residents to integrate their electric meters into Home Assistant. This integration will create a sensor for each meter that shows the current reading.
+
+On its own this sensor is not particularly useful. However, combined with a [`utility_meter`](/integrations/utility_meter/) sensor you can obtain usage over a month, for example.
+
+## Setup
+
+Any Texas electricity consumer can register an account.
+
+1. Go to [Smart Meter Texas](https://www.smartmetertexas.com/)
+2. Select _Sign Up_
+3. Choose _residential_ as your account type
+4. You will need following details which can be found on your electric bill.
+    - The name of your retail electric provider
+    - Your meter number
+    - Your ESIID (Electric Service Identifier)
+
+<div class='note'>
+Due to API limits, this sensor refreshes once per hour. The limit is 24 meter readings per calendar day.
+</div>
+
+## Configuration
+
+This integration can be configured from the frontend.
+
+Menu: _Configuration > Integrations_, select the `+` button and search for _Smart Meter Texas_.