config: add BME280 documentation

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

config/sample-macros.cfg

@@ -115,3 +115,35 @@ gcode:
     G91
     G1 E-50 F1000
     RESTORE_GCODE_STATE NAME=M600_state
+
+######################################################################
+# BME280 Environmental Sensor
+######################################################################
+
+# The macro below assumes you have a BME280 sensor_type defined in one
+# of the applicable sections in printer.cfg, such as:
+#
+#[temperature_sensor my_sensor]
+#sensor_type: BME280
+#gcode_id: AMB
+#
+# Note the format of the parameter SENSOR in the macro below.  The BME280
+# sensor status can be accessed using the format "bme280 <section_name>".
+# The example section above is named "my_sensor", thus the bme280 can be
+# queried as follows:
+#
+# QUERY_BME280 SENSOR='bme280 my_sensor'
+#
+# Since a default parameter is defined one could simply enter QUERY_BME280
+# as well.
+
+[gcode_macro QUERY_BME280]
+default_parameter_SENSOR: bme280 my_sensor
+gcode:
+    {printer.gcode.action_respond_info(
+        "Temperature: %.2f C\n"
+        "Pressure: %.2f hPa\n"
+        "Humidity: %.2f%%" % (
+            printer[SENSOR].temperature,
+            printer[SENSOR].pressure,
+            printer[SENSOR].humidity))}