Add changelog.md

[dido18]

Motivation

Add a changelog.md file to keep track of the changes with a human-friendly explanation.

Change description

Additional Notes

Reviewer checklist

• PR addresses a single concern.
• PR title and description are properly filled.
• Changes will be merged in main.
• Changes are covered by tests.
• Logging is meaningful in case of troubleshooting.

[lucarin91]

I think we should also include this in the .deb package.
That should be installed in /usr/share/doc/arduino-app-cli/CHANGELOG.md.gz, better if gzipped

I would also move this to the root of the folder

[per1234]

Is the responsibility for maintaining the file on the contributor (i.e., changelog entry must be included in the PR), or on the project maintainer/release manager (i.e., they must write the changelog at some point(s) prior to the release)?

If the former, it should be documented in the pull request guide:

https://github.com/arduino/arduino-app-cli/blob/main/docs/contributor-guide/pull-requests.md#pull-request-guide

If the latter, it should be documented in a release procedure document.

Even if the responsibility is on the contributor, the release manager will still need to change the heading from [Unreleased] as part of the release procedure, so a step is required in the release procedure document regardless.

I recommend hosting the release procedure document in this repository. The release procedure document of the Arduino IDE repository can serve as a reference:

https://github.com/arduino/arduino-ide/blob/main/docs/internal/release-procedure.md