Release notes (changelogs) are primarily used to notify users of changes between versions. Perhaps a new useful feature is available, or an old feature was deprecated.
The first released version has no changes. The release notes are then quite simple:
- 🎉 first release!
Anything else would be confusing, in my experience.
Sometimes, the v1.0 isn't the first release. This is especially the case for open-source projects where v0.x releases are common. In that case, the v1.0 release would have some changes to note. At a minimum, a v1.0 release signifies that the API is now stable, which is a noteworthy change.
For release notes on a website or a mailing list, these should be written less like a technical changelog and more like a press release. The first release is an opportunity to:
- showcase why your software is awesome,
- list differences to competing software, and
- give an overview of your full documentation.
If your changelog is embedded into an application, the first release should probably display a “get started” guide in this space.