zephyr: Add README.
zephyr: Add README.

MrSurly/micropython-esp32,puuu/micropython,pramasoul/micropython,dmazzella/micropython,cwyark/micropython,kerneltask/micropython,hiway/micropython,PappaPeppar/micropython,swegener/micropython,dxxb/micropython,trezor/micropython,MrSurly/micropython-esp32,matthewelse/micropython,oopy/micropython,lowRISC/micropython,deshipu/micropython,adafruit/micropython,chrisdearman/micropython,adafruit/micropython,HenrikSolver/micropython,tuc-osg/micropython,cwyark/micropython,henriknelson/micropython,alex-robbins/micropython,henriknelson/micropython,Timmenem/micropython,micropython/micropython-esp32,adafruit/circuitpython,tralamazza/micropython,SHA2017-badge/micropython-esp32,PappaPeppar/micropython,dxxb/micropython,trezor/micropython,toolmacher/micropython,pozetroninc/micropython,bvernoux/micropython,toolmacher/micropython,AriZuu/micropython,ryannathans/micropython,dxxb/micropython,infinnovation/micropython,tobbad/micropython,swegener/micropython,blazewicz/micropython,puuu/micropython,matthewelse/micropython,chrisdearman/micropython,chrisdearman/micropython,torwag/micropython,lowRISC/micropython,puuu/micropython,adafruit/circuitpython,chrisdearman/micropython,infinnovation/micropython,infinnovation/micropython,Timmenem/micropython,AriZuu/micropython,henriknelson/micropython,selste/micropython,alex-march/micropython,micropython/micropython-esp32,dmazzella/micropython,oopy/micropython,PappaPeppar/micropython,mhoffma/micropython,kerneltask/micropython,blazewicz/micropython,jmarcelino/pycom-micropython,oopy/micropython,pozetroninc/micropython,ryannathans/micropython,bvernoux/micropython,SHA2017-badge/micropython-esp32,AriZuu/micropython,AriZuu/micropython,alex-march/micropython,kerneltask/micropython,adafruit/micropython,chrisdearman/micropython,hiway/micropython,MrSurly/micropython,torwag/micropython,cwyark/micropython,kerneltask/micropython,tobbad/micropython,cwyark/micropython,tobbad/micropython,torwag/micropython,micropython/micropython-esp32,mhoffma/micropython,selste/micropython,pozetroninc/micropython,hosaka/micropython,TDAbboud/micropython,hosaka/micropython,lowRISC/micropython,mhoffma/micropython,tralamazza/micropython,jmarcelino/pycom-micropython,deshipu/micropython,TDAbboud/micropython,adafruit/circuitpython,adafruit/circuitpython,selste/micropython,MrSurly/micropython,pramasoul/micropython,toolmacher/micropython,ryannathans/micropython,Timmenem/micropython,PappaPeppar/micropython,jmarcelino/pycom-micropython,dxxb/micropython,jmarcelino/pycom-micropython,puuu/micropython,ryannathans/micropython,TDAbboud/micropython,adafruit/circuitpython,trezor/micropython,cwyark/micropython,MrSurly/micropython-esp32,micropython/micropython-esp32,MrSurly/micropython-esp32,matthewelse/micropython,selste/micropython,hosaka/micropython,tuc-osg/micropython,pozetroninc/micropython,PappaPeppar/micropython,SHA2017-badge/micropython-esp32,dmazzella/micropython,dmazzella/micropython,puuu/micropython,henriknelson/micropython,tobbad/micropython,swegener/micropython,tralamazza/micropython,jmarcelino/pycom-micropython,pfalcon/micropython,deshipu/micropython,mhoffma/micropython,SHA2017-badge/micropython-esp32,deshipu/micropython,TDAbboud/micropython,Timmenem/micropython,Peetz0r/micropython-esp32,Timmenem/micropython,Peetz0r/micropython-esp32,Peetz0r/micropython-esp32,trezor/micropython,tuc-osg/micropython,pramasoul/micropython,oopy/micropython,AriZuu/micropython,MrSurly/micropython,Peetz0r/micropython-esp32,alex-robbins/micropython,alex-march/micropython,pfalcon/micropython,SHA2017-badge/micropython-esp32,blazewicz/micropython,pramasoul/micropython,dxxb/micropython,alex-march/micropython,kerneltask/micropython,pramasoul/micropython,bvernoux/micropython,hosaka/micropython,tuc-osg/micropython,alex-robbins/micropython,pozetroninc/micropython,selste/micropython,toolmacher/micropython,bvernoux/micropython,pfalcon/micropython,Peetz0r/micropython-esp32,alex-robbins/micropython,alex-march/micropython,adafruit/circuitpython,hiway/micropython,blazewicz/micropython,MrSurly/micropython,lowRISC/micropython,henriknelson/micropython,mhoffma/micropython,swegener/micropython,trezor/micropython,tralamazza/micropython,hiway/micropython,adafruit/micropython,lowRISC/micropython,TDAbboud/micropython,matthewelse/micropython,HenrikSolver/micropython,matthewelse/micropython,HenrikSolver/micropython,pfalcon/micropython,ryannathans/micropython,deshipu/micropython,infinnovation/micropython,oopy/micropython,MrSurly/micropython-esp32,micropython/micropython-esp32,HenrikSolver/micropython,pfalcon/micropython,alex-robbins/micropython,hosaka/micropython,tuc-osg/micropython,torwag/micropython,matthewelse/micropython,swegener/micropython,hiway/micropython,MrSurly/micropython,torwag/micropython,bvernoux/micropython,tobbad/micropython,infinnovation/micropython,toolmacher/micropython,HenrikSolver/micropython,blazewicz/micropython,adafruit/micropython