Update for TTN v3

[benolayinka]

Hey @AmedeeBulle ! Great write up!

We’ve released a new version of our network server, called The Things Stack. We’re in the process of migrating our user base to the new platform and we will sunset the old environment later this year.

Can I support you updating the documentation to use The Things Stack (i.e. The Things Network v3)? You can start using The Things Stack free of charge by using the Community Edition: https://console.cloud.thethings.network/

Looking forward to hearing from you