Describe new auth-related features in readme

[f1ames]

This PR describes new auth-related features.

Changes

• Added section about synchronization feature and setup.
• Added description of new commands and config option to readme.
• Updated changelog.

Fixes

• None.

Checklist

• [x] tested locally
• [ ] added new dependencies
• [x] updated the docs
• [ ] added a test

[f1ames]

Went through the changes together with @julioramosest and agreed it's good for now 👍