Increment patch version to v0.6.1

Increment minor version to v0.6.0

Short name and Baseline high date have been added to the schema:
web-platform-dx#545
web-platform-dx#593

Many features have also been added.

web-features 0.5.1

web-features 0.5.0

web-features 0.5.0-alpha.2

web-features 0.5.0-alpha.1

web-features 0.5.0-alpha.0

web-features 0.4.1

web-features 0.4.0

web-features 0.3.0