README: Add short overview of Python features supported.
README: Add short overview of Python features supported.

Also, "upgrade" project to "early beta", and elaborate pyboard description.

TDAbboud/micropython,misterdanb/micropython,alex-march/micropython,hiway/micropython,SHA2017-badge/micropython-esp32,ernesto-g/micropython,galenhz/micropython,oopy/micropython,warner83/micropython,henriknelson/micropython,cnoviello/micropython,utopiaprince/micropython,xyb/micropython,lowRISC/micropython,blmorris/micropython,ahotam/micropython,adafruit/micropython,stonegithubs/micropython,ganshun666/micropython,blazewicz/micropython,lowRISC/micropython,HenrikSolver/micropython,kostyll/micropython,ChuckM/micropython,SHA2017-badge/micropython-esp32,TDAbboud/micropython,jlillest/micropython,ChuckM/micropython,firstval/micropython,Vogtinator/micropython,swegener/micropython,turbinenreiter/micropython,ernesto-g/micropython,ryannathans/micropython,MrSurly/micropython-esp32,micropython/micropython-esp32,skybird6672/micropython,cnoviello/micropython,cnoviello/micropython,blazewicz/micropython,SHA2017-badge/micropython-esp32,lowRISC/micropython,noahwilliamsson/micropython,martinribelotta/micropython,deshipu/micropython,slzatz/micropython,KISSMonX/micropython,mhoffma/micropython,infinnovation/micropython,pramasoul/micropython,SungEun-Steve-Kim/test-mp,hosaka/micropython,torwag/micropython,galenhz/micropython,heisewangluo/micropython,misterdanb/micropython,infinnovation/micropython,AriZuu/micropython,jimkmc/micropython,ericsnowcurrently/micropython,mianos/micropython,mhoffma/micropython,adafruit/micropython,puuu/micropython,pramasoul/micropython,kostyll/micropython,PappaPeppar/micropython,emfcamp/micropython,suda/micropython,swegener/micropython,hiway/micropython,pozetroninc/micropython,ericsnowcurrently/micropython,slzatz/micropython,henriknelson/micropython,xhat/micropython,mianos/micropython,alex-robbins/micropython,suda/micropython,noahwilliamsson/micropython,tdautc19841202/micropython,cwyark/micropython,paul-xxx/micropython,heisewangluo/micropython,AriZuu/micropython,warner83/micropython,xhat/micropython,drrk/micropython,dmazzella/micropython,jlillest/micropython,oopy/micropython,stonegithubs/micropython,dinau/micropython,matthewelse/micropython,danicampora/micropython,toolmacher/micropython,mpalomer/micropython,adafruit/circuitpython,PappaPeppar/micropython,cwyark/micropython,aethaniel/micropython,kostyll/micropython,vitiral/micropython,aethaniel/micropython,chrisdearman/micropython,omtinez/micropython,adamkh/micropython,cloudformdesign/micropython,HenrikSolver/micropython,praemdonck/micropython,selste/micropython,mianos/micropython,paul-xxx/micropython,redbear/micropython,SungEun-Steve-Kim/test-mp,matthewelse/micropython,blmorris/micropython,danicampora/micropython,dxxb/micropython,galenhz/micropython,trezor/micropython,ericsnowcurrently/micropython,noahchense/micropython,alex-robbins/micropython,KISSMonX/micropython,AriZuu/micropython,mpalomer/micropython,adafruit/micropython,vriera/micropython,aethaniel/micropython,utopiaprince/micropython,ganshun666/micropython,pramasoul/micropython,MrSurly/micropython-esp32,selste/micropython,MrSurly/micropython,paul-xxx/micropython,praemdonck/micropython,adafruit/circuitpython,oopy/micropython,redbear/micropython,infinnovation/micropython,MrSurly/micropython,KISSMonX/micropython,xhat/micropython,bvernoux/micropython,firstval/micropython,neilh10/micropython,MrSurly/micropython-esp32,PappaPeppar/micropython,blazewicz/micropython,lowRISC/micropython,supergis/micropython,suda/micropython,PappaPeppar/micropython,kerneltask/micropython,lbattraw/micropython,noahwilliamsson/micropython,puuu/micropython,TDAbboud/micropython,alex-march/micropython,adamkh/micropython,Timmenem/micropython,ryannathans/micropython,dmazzella/micropython,vitiral/micropython,micropython/micropython-esp32,warner83/micropython,jmarcelino/pycom-micropython,infinnovation/micropython,pfalcon/micropython,emfcamp/micropython,MrSurly/micropython-esp32,hosaka/micropython,chrisdearman/micropython,adamkh/micropython,orionrobots/micropython,trezor/micropython,drrk/micropython,skybird6672/micropython,turbinenreiter/micropython,redbear/micropython,omtinez/micropython,ericsnowcurrently/micropython,stonegithubs/micropython,mhoffma/micropython,SHA2017-badge/micropython-esp32,dxxb/micropython,ryannathans/micropython,slzatz/micropython,swegener/micropython,misterdanb/micropython,AriZuu/micropython,jmarcelino/pycom-micropython,mgyenik/micropython,methoxid/micropystat,mgyenik/micropython,xuxiaoxin/micropython,SungEun-Steve-Kim/test-mp,henriknelson/micropython,kostyll/micropython,heisewangluo/micropython,chrisdearman/micropython,ernesto-g/micropython,KISSMonX/micropython,swegener/micropython,pozetroninc/micropython,kerneltask/micropython,micropython/micropython-esp32,kerneltask/micropython,omtinez/micropython,ChuckM/micropython,cwyark/micropython,praemdonck/micropython,ruffy91/micropython,firstval/micropython,vitiral/micropython,vriera/micropython,dxxb/micropython,rubencabrera/micropython,swegener/micropython,hosaka/micropython,alex-march/micropython,selste/micropython,xyb/micropython,heisewangluo/micropython,hosaka/micropython,ChuckM/micropython,matthewelse/micropython,micropython/micropython-esp32,dinau/micropython,ernesto-g/micropython,EcmaXp/micropython,torwag/micropython,ahotam/micropython,jmarcelino/pycom-micropython,mgyenik/micropython,omtinez/micropython,cnoviello/micropython,supergis/micropython,cloudformdesign/micropython,blmorris/micropython,tuc-osg/micropython,deshipu/micropython,blmorris/micropython,xhat/micropython,utopiaprince/micropython,feilongfl/micropython,tdautc19841202/micropython,drrk/micropython,redbear/micropython,ceramos/micropython,turbinenreiter/micropython,noahwilliamsson/micropython,matthewelse/micropython,skybird6672/micropython,cwyark/micropython,tobbad/micropython,EcmaXp/micropython,mgyenik/micropython,pfalcon/micropython,mpalomer/micropython,pfalcon/micropython,omtinez/micropython,micropython/micropython-esp32,galenhz/micropython,noahchense/micropython,methoxid/micropystat,dhylands/micropython,bvernoux/micropython,aethaniel/micropython,alex-robbins/micropython,blazewicz/micropython,dhylands/micropython,mpalomer/micropython,noahchense/micropython,SHA2017-badge/micropython-esp32,dxxb/micropython,ceramos/micropython,martinribelotta/micropython,skybird6672/micropython,ceramos/micropython,neilh10/micropython,xuxiaoxin/micropython,martinribelotta/micropython,jimkmc/micropython,AriZuu/micropython,SungEun-Steve-Kim/test-mp,utopiaprince/micropython,mhoffma/micropython,deshipu/micropython,suda/micropython,henriknelson/micropython,cloudformdesign/micropython,trezor/micropython,toolmacher/micropython,stonegithubs/micropython,rubencabrera/micropython,tuc-osg/micropython,suda/micropython,dhylands/micropython,feilongfl/micropython,alex-march/micropython,adafruit/circuitpython,methoxid/micropystat,MrSurly/micropython,vriera/micropython,ahotam/micropython,pramasoul/micropython,mianos/micropython,utopiaprince/micropython,heisewangluo/micropython,dhylands/micropython,galenhz/micropython,pozetroninc/micropython,chrisdearman/micropython,deshipu/micropython,dinau/micropython,misterdanb/micropython,praemdonck/micropython,hosaka/micropython,tobbad/micropython,torwag/micropython,skybird6672/micropython,trezor/micropython,mpalomer/micropython,bvernoux/micropython,tuc-osg/micropython,Timmenem/micropython,xyb/micropython,KISSMonX/micropython,HenrikSolver/micropython,xyb/micropython,ganshun666/micropython,cloudformdesign/micropython,drrk/micropython,Timmenem/micropython,methoxid/micropystat,ruffy91/micropython,kerneltask/micropython,neilh10/micropython,pfalcon/micropython,henriknelson/micropython,ganshun666/micropython,puuu/micropython,drrk/micropython,vriera/micropython,pozetroninc/micropython,mhoffma/micropython,jlillest/micropython,jmarcelino/pycom-micropython,paul-xxx/micropython,xuxiaoxin/micropython,xuxiaoxin/micropython,lbattraw/micropython,blmorris/micropython,ahotam/micropython,orionrobots/micropython,ruffy91/micropython,orionrobots/micropython,ruffy91/micropython,turbinenreiter/micropython,pozetroninc/micropython,lbattraw/micropython,xhat/micropython,xuxiaoxin/micropython,toolmacher/micropython,jimkmc/micropython,ChuckM/micropython,tobbad/micropython,matthewelse/micropython,slzatz/micropython,adamkh/micropython,vitiral/micropython,puuu/micropython,Vogtinator/micropython,bvernoux/micropython,ahotam/micropython,Timmenem/micropython,martinribelotta/micropython,noahchense/micropython,neilh10/micropython,EcmaXp/micropython,methoxid/micropystat,EcmaXp/micropython,stonegithubs/micropython,MrSurly/micropython,turbinenreiter/micropython,blazewicz/micropython,kostyll/micropython,rubencabrera/micropython,dinau/micropython,tdautc19841202/micropython,vriera/micropython,Vogtinator/micropython,dhylands/micropython,noahwilliamsson/micropython,Peetz0r/micropython-esp32,selste/micropython,supergis/micropython,supergis/micropython,dmazzella/micropython,warner83/micropython,oopy/micropython,toolmacher/micropython,jimkmc/micropython,Vogtinator/micropython,adafruit/circuitpython,supergis/micropython,paul-xxx/micropython,SungEun-Steve-Kim/test-mp,alex-robbins/micropython,tuc-osg/micropython,tralamazza/micropython,vitiral/micropython,adafruit/micropython,redbear/micropython,tuc-osg/micropython,jlillest/micropython,deshipu/micropython,mianos/micropython,danicampora/micropython,alex-march/micropython,adafruit/circuitpython,mgyenik/micropython,misterdanb/micropython,Vogtinator/micropython,toolmacher/micropython,lowRISC/micropython,ganshun666/micropython,alex-robbins/micropython,Peetz0r/micropython-esp32,Peetz0r/micropython-esp32,tdautc19841202/micropython,martinribelotta/micropython,firstval/micropython,tralamazza/micropython,ericsnowcurrently/micropython,matthewelse/micropython,torwag/micropython,tobbad/micropython,bvernoux/micropython,emfcamp/micropython,emfcamp/micropython,ruffy91/micropython,adafruit/micropython,hiway/micropython,warner83/micropython,cnoviello/micropython,chrisdearman/micropython,praemdonck/micropython,jmarcelino/pycom-micropython,trezor/micropython,lbattraw/micropython,ceramos/micropython,xyb/micropython,danicampora/micropython,selste/micropython,PappaPeppar/micropython,oopy/micropython,orionrobots/micropython,feilongfl/micropython,hiway/micropython,slzatz/micropython,tobbad/micropython,torwag/micropython,MrSurly/micropython,rubencabrera/micropython,hiway/micropython,adamkh/micropython,emfcamp/micropython,neilh10/micropython,adafruit/circuitpython,HenrikSolver/micropython,ceramos/micropython,jimkmc/micropython,Timmenem/micropython,Peetz0r/micropython-esp32,feilongfl/micropython,pramasoul/micropython,firstval/micropython,tralamazza/micropython,dxxb/micropython,puuu/micropython,danicampora/micropython,feilongfl/micropython,lbattraw/micropython,Peetz0r/micropython-esp32,tdautc19841202/micropython,orionrobots/micropython,infinnovation/micropython,aethaniel/micropython,TDAbboud/micropython,ryannathans/micropython,tralamazza/micropython,jlillest/micropython,cwyark/micropython,TDAbboud/micropython,dinau/micropython,rubencabrera/micropython,EcmaXp/micropython,cloudformdesign/micropython,dmazzella/micropython,ernesto-g/micropython,kerneltask/micropython,ryannathans/micropython,MrSurly/micropython-esp32,noahchense/micropython,HenrikSolver/micropython,pfalcon/micropython