feat: Add HTU31D Documentation (#3397)

* feat: Add HTU31D Documentation

This commit adds documentation for the HTU31D component.

* Fix image size

---------

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

components/sensor/htu31d.rst

@@ -0,0 +1,62 @@
+HTU31D Temperature & Humidity Sensor
+=====================================================
+
+.. seo::
+    :description: Instructions for setting up HTU31D temperature and humidity sensors.
+    :image: htu31d.jpg
+    :keywords: HTU31D
+
+The HTU31D Temperature & Humidity component allows you to use HTU31D sensors with
+ESPHome. The :ref:`I²C Bus <i2c>` is required to be set up in your configuration for this sensor to work.
+
+
+Example sensors:
+
+- (`Adafruit <https://www.adafruit.com/product/4832>`__)
+
+.. figure:: images/htu31d.jpg
+    :align: center
+    :width: 50.0%
+
+    HTU31D Temperature & Humidity Sensor. Image by `Adafruit`_.
+
+.. _Adafruit: https://www.adafruit.com/product/4832
+
+.. figure:: images/temperature-humidity.png
+    :align: center
+    :width: 80.0%
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    sensor:
+      - platform: htu31d
+        temperature:
+          name: "Temperature"
+        humidity:
+          name: "Humidity"
+
+Configuration variables:
+------------------------
+
+- **temperature** (*Optional*): The information for the temperature sensor.
+  All options from :ref:`Sensor <config-sensor>`.
+
+- **humidity** (*Optional*): The information for the humidity sensor.
+  All options from :ref:`Sensor <config-sensor>`.
+
+- **update_interval** (*Optional*, :ref:`config-time`): The interval to check the sensor. Defaults to ``60s``.
+
+See Also
+--------
+
+- :ref:`sensor-filters`
+- :doc:`absolute_humidity`
+- :doc:`htu21d`
+- :doc:`dht`
+- :doc:`dht12`
+- :doc:`hdc1080`
+- :doc:`sht3xd`
+- :apiref:`htu31d/htu31d.h`
+- `i2cdevlib <https://github.com/jrowberg/i2cdevlib>`__ by `Jeff Rowberg <https://github.com/jrowberg>`__
+- :ghedit:`Edit`

index.rst

@@ -323,6 +323,7 @@ Environmental
     Honeywell ABP2 I2C, components/sensor/honeywellabp2_i2c, honeywellabp.jpg, Pressure & Temperature
     Honeywell HIH I2C, components/sensor/honeywell_hih_i2c, honeywellhih.jpg, Temperature & Humidity
     HTU21D / Si7021 / SHT21, components/sensor/htu21d, htu21d.jpg, Temperature & Humidity
+    HTU31D, components/sensor/htu31d, htu31d.jpg, Temperature & Humidity
     Hydreon Rain Sensor, components/sensor/hydreon_rgxx, hydreon_rg9.jpg, Rain
     Inkbird IBS-TH1 Mini, components/sensor/inkbird_ibsth1_mini, inkbird_isbth1_mini.jpg, Temperature & Humidity
     Internal Temperature, components/sensor/internal_temperature, thermometer.svg, Temperature, dark-invert