Add Licence and metadata in the header

circuitpython/main.py

@@ -1,4 +1,24 @@
-# Weather and GPS logger
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+##########################
+# Weather and GPS logger #
+##########################
+
+# Use with:
+# * Adafruit Feather M0 Express
+# * Adafruit Ultimate GPS FeatherWing
+# * Bosch BME280 sensor (air temperature, humidity, atmospheric pressure) on I2C
 
 ##########
 # config #