introduce Mintlify and the changelog to the development team

[dangrondahl]

Help the development team get familiar with Mintlify as the new docs platform,
with a focus on the changelog and how to contribute to docs going forward.

Tasks

• Run a walkthrough session covering Mintlify basics and the new workflow
• Demonstrate the changelog and how to add entries
• Consider adding the `changelog-creator` skill to the repo so Claude Code
  can generate changelog entries from git history automatically
• Document the contribution workflow in `CLAUDE.md` or a `CONTRIBUTING.md`

[dangrondahl]

@AlexKantor87 suggested having a small workshop. Also address how we do conventional commits for ease of release notes in the terraform-provider-kosli