Update README.md (#5519)
Update README.md (#5519)

clarify some points, add links, add doc/conf.py
esp8266/Arduino,Lan-Hekary/Arduino,Lan-Hekary/Arduino,Lan-Hekary/Arduino,sticilface/Arduino,sticilface/Arduino,esp8266/Arduino,sticilface/Arduino,sticilface/Arduino,esp8266/Arduino,esp8266/Arduino,Lan-Hekary/Arduino,Lan-Hekary/Arduino,sticilface/Arduino,esp8266/Arduino