readme: mention nrfutil install device

nrfutil: cache to avoid frequent calls

add list --nrfutil-cmd

correct nrf serial port check fix if no nrfutil

serial: distinguish nrf52840dk ports

serial: add debugging list of ports

Merge pull request #138 from radnvlad/feature/fix_useragent

Force a User-Agent string that is NOT the default Python-urlib. This led to the connection being dropped.

add linkserver to the readme

escape $ correctly

nrfutil: make logs debug so they dont always print

add support for NXP LinkServer

sync requirements.txt and pyproject.toml

Merge pull request #135 from tock/nrfutil-bradjc

update all docs