package.json: specify the files to include

[XhmikosR]

This is the opposite of what happened before

C:\Users\xmr\Desktop\gulp-sass>npm pack --dry
npm notice
npm notice package: [email protected]
npm notice === Tarball Contents ===
npm notice 1.1kB LICENSE
npm notice 5.9kB index.js
npm notice 1.2kB package.json
npm notice 3.0kB CHANGELOG.md
npm notice 8.5kB README.md
npm notice === Tarball Details ===
npm notice name:          gulp-sass
npm notice version:       5.0.0
npm notice filename:      gulp-sass-5.0.0.tgz
npm notice package size:  6.8 kB
npm notice unpacked size: 19.7 kB
npm notice shasum:        2850f922bb79cb9cf2410ccec28ed7daa1748e16
npm notice integrity:     sha512-lNz3NenbCVi42[...]d2nudAhxXvr7A==
npm notice total files:   5
npm notice
gulp-sass-5.0.0.tgz

[xzyfer]

Thanks