Add pyserial to environment dependencies

Signed-off-by: Soren Friis <soren.friis@intel.com>

BUILDING.md

@@ -36,8 +36,10 @@ or build with the Arduino GUI. I prefer make, but both will work.
  - cd RemoteIDModule
  - make upload
 
-If board does not flash, hold-down BOOT pushbutton on pcb while pressing RESET pushbutton briefly [to force it into bootloader mode] and retry.
-done, ESP32-S3 is now running and emitting test/demo remote-id bluetooth
+If the board does not flash, hold-down the BOOT pushbutton on the PCB while pressing the RESET pushbutton briefly [to force it into bootloader mode] and retry.
+The ESP32-S3 is now running and emitting test/demo remote-id bluetooth
+
+If you get an error about missing serial support from python, install it with `python -m pip install pyserial`.
 
 ## Building with the Arduino GUI
 

scripts/install_build_env.sh

@@ -3,6 +3,7 @@
 python3 -m pip install empy
 python3 -m pip install pymavlink
 python3 -m pip install dronecan
+python3 -m pip install pyserial
 wget https://downloads.arduino.cc/arduino-cli/arduino-cli_0.26.0_Linux_64bit.tar.gz
 mkdir -p bin
 (cd bin && tar xvzf ../arduino-cli_0.26.0_Linux_64bit.tar.gz)