Log level (#4341)

Co-authored-by: Jesse Hills <[email protected]>

Author: briancw

guides/getting_started_command_line.rst

@@ -237,6 +237,8 @@ To start the ESPHome dashboard, simply start ESPHome with the following command
 
 After that, you will be able to access the dashboard through ``localhost:6052``.
 
+Logging level can be set with the env var `ESPHOME_LOG_LEVEL` (default is `INFO`).
+
 .. figure:: images/dashboard_states.png
 
 See Also