Add licenses to README.md

README.md

@@ -127,5 +127,14 @@ Here are some links to coverage and additional tutorials for using `arduino-pico
 # Contributing
 If you want to contribute or have bugfixes, drop me a note at <earlephilhower@yahoo.com> or open an issue/PR here.
 
+# Licensing and Credits
+* The [Arduino IDE and ArduinoCore-API](https://arduino.cc) are developed and maintained by the Arduino team. The IDE is licensed under GPL.
+* The [RP2040 GCC-based toolchain](https://github.com/earlephilhower/pico-quick-toolchain) is licensed under under the GPL.
+* The [Pico-SDK](https://github.com/raspberrypi/pico-sdk) and [Pico-Extras](https://github.com/raspberrypi/pico-extras) are by Raspberry Pi (Trading) Ltd and licensed under the BSD 3-Clause license.
+* [Arduino-Pico](https://github.com/earlephilhower/arduino-pico) core files are licenses under the LGPL.
+* [LittleFS](https://github.com/ARMmbed/littlefs) library written by ARM Limited and released under the [BSD 3-clause license](https://github.com/ARMmbed/littlefs/blob/master/LICENSE.md).
+* [UF2CONV.PY](https://github.com/microsoft/uf2) is by Microsoft Corporatio and licensed under the MIT license.
+* Some filesystem code taken from the [ESP8266 Arduino Core](https://github.com/esp8266/Arduino) and licensed under the LGPL.
+
 -Earle F. Philhower, III
  earlephilhower@yahoo.com