syncthing/relnotes/v2.md

This release is also available as:

• APT repository: https://apt.syncthing.net/

• Docker image: docker.io/syncthing/syncthing:{{.version}} or ghcr.io/syncthing/syncthing:{{.version}} ({docker,ghcr}.io/syncthing/syncthing:2 to follow just the major version)