Add documentation for MCP9808 sensor (#691)

* Add documentation for MCP9808 sensor

* Compress index image

* Add address configuration variable

Co-authored-by: Otto Winter <otto@otto-winter.com>

components/sensor/mcp9808.rst

@@ -0,0 +1,56 @@
+MCP9808 Temperature Sensor
+==========================
+
+.. seo::
+    :description: Instructions for setting up MCP9808 temperature sensor.
+    :image: mcp9808.jpg
+    :keywords: MCP9808
+
+The MCP9808 Temperature sensor allows you to use your MCP9808
+(`datasheet <http://ww1.microchip.com/downloads/en/DeviceDoc/25095A.pdf>`__,
+`Adafruit <https://www.adafruit.com/product/1782>`__) sensors with
+ESPHome. The :ref:`I²C Bus <i2c>` is
+required to be set up in your configuration for this sensor to work.
+
+.. figure:: images/mcp9808-full.jpg
+    :align: center
+    :target: `Adafruit`_
+    :width: 50.0%
+
+    MCP9808 Temperature Sensor. Image by `Adafruit`_.
+
+.. _Adafruit: https://www.adafruit.com/product/1782
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    sensor:
+      - platform: mcp9808
+        name: "Living Room Temperature"
+        update_interval: 60s
+
+Configuration variables:
+------------------------
+
+- **temperature** (**Required**): The information for the temperature sensor.
+
+  - **name** (**Required**, string): The name for the temperature sensor.
+  - **id** (*Optional*, :ref:`config-id`): Set the ID of this sensor for use in lambdas.
+  - All other options from :ref:`Sensor <config-sensor>`.
+
+- **address** (*Optional*, int): Manually specify the I²C address of the sensor. Defaults to ``0x18``.
+- **update_interval** (*Optional*, :ref:`config-time`): The interval to check the sensor. Defaults to ``60s``.
+
+
+See Also
+--------
+
+- :ref:`sensor-filters`
+- :doc:`dht`
+- :doc:`dht12`
+- :doc:`htu21d`
+- :doc:`sht3xd`
+- :doc:`hdc1080`
+- :apiref:`mcp9808/mcp9808.h`
+- `MCP9808 Library <https://github.com/adafruit/Adafruit_MCP9808_Library>`__ by `AdaFruit <https://www.adafruit.com/>`__
+- :ghedit:`Edit`

index.rst

@@ -130,6 +130,7 @@ Sensor Components
     MAX31856, components/sensor/max31856, max31856.jpg
     MAX31865, components/sensor/max31865, max31865.jpg
     MAX6675, components/sensor/max6675, max6675.jpg
+    MCP9808, components/sensor/mcp9808, mcp9808.jpg
     MH-Z19, components/sensor/mhz19, mhz19.jpg
     MPU6050, components/sensor/mpu6050, mpu6050.jpg
     MQTT Subscribe, components/sensor/mqtt_subscribe, mqtt.png