Update README.md (#383)
Update README.md (#383)

BREAKING CHANGE: It's no longer allowed to omit the '-loader' suffix when using loaders.
                 You need to specify 'raw-loader' instead of 'raw',
                 see https://webpack.js.org/guides/migrating/#automatic-loader-module-name-extension-removed
FormidableLabs/spectacle,FormidableLabs/spectacle,lowsky/spectacle,lowsky/spectacle