Add temporary esp-idf example

changelog/2021.10.0.rst

@@ -24,6 +24,18 @@ ESPHome 2021.10.0 - 20th October 2021
 ESP-IDF
 -------
 
+Docs still to be written before release on how to use ESP-IDF, but here is a quick example:
+
+.. code-block:: yaml
+
+    esphome:
+      name: livingroom
+
+    esp32:
+      board: <BOARD_TYPE>
+      framework:
+        type: esp-idf
+
 A huge effort has been put into reorganising, restructuring and rewriting a whole lot of code
 to allow ESP32 based boards to be compiled using ESP-IDF as the framework instead of Arduino.
 This allows ESPHome to keep up with new features and support for new ESP32 based chips