This contents of this repo was moved to the Storybook monorepo and the NPM package name has been changed.
- The old name of the package was: @kadira/storybook/addons
- The new name of the package is: @storybook/addons
- The location of the code is: https://github.com/storybooks/storybook/tree/master/lib/addons
The repo you're looking at now is out of date and no longer maintained.