adr init
This will initialise the repo and create a doc/adr directory (you can override this) with the first ADR explaining that we will be recording ADRs in this repo :)
adr new Use JUnit 4.12 for testing
This adds a new ADR (automatically numbered as number 0002) that records our decision to use JUnit 4.12
adr new -s 2 Use JUnit 5 for testing
This creates an additional ADR that supersedes the old one (number 2). Both ADRs refer to each other.