update gostun to 1.21.1 and updated path from github.com/gortc/stun to gortc.io/stun

fix build script wrong directory

update filename

update Azure DevOps CI badge image link

update CI definition

add example build script

update README

make OpenDNS DNS query work

fix some newbie errors

update OpenDNS DNS code from @m13253

update README

update README

update README

update help

first commit