Add kmeans-colors to Scoop Extras

[oxjihun]

Scoop is a command-line installer for Windows. I wrote a following manifest that, once added to any of the Scoop's buckets such as Extras, would enable installing kmeans-colors via scoop install kmeans-colors.

{
    "version": "0.6.0",
    "description": "k-means clustering library and binary to find dominant colors in images",
    "homepage": "https://github.com/okaneco/kmeans-colors",
    "license": "MIT",
    "architecture": {
        "64bit": {
            "url": "https://github.com/okaneco/kmeans-colors/releases/download/0.6.0-binary/kmeans_colors-0.6.0-binary-windows-x86_64.tar.gz",
            "hash": "0d9060a8af1ebe19812618760b8e9f1f7907d925e523085b1a68d0ba9bcaa270"
        }
    },
    "bin": "kmeans_colors.exe",
    "checkver": "github",
    "autoupdate": {
        "architecture": {
            "64bit": {
                "url": "https://github.com/okaneco/kmeans-colors/releases/download/$version-binary/kmeans_colors-$version-binary-windows-x86_64.tar.gz",
                "hash": {
                    "url": "https://github.com/okaneco/kmeans-colors/releases/download/$version-binary/kmeans_colors-$version-binary-windows-x86_64.sha256"
                }
            }
        }
    }
}

I am writing this issue to learn about how you might feel about this before actually making a PR there!