Electron-Forge custom protocol definition for osx

electron-forge-protocol-config.json

"config": {
    "forge": {
      "make_targets": {
        "win32": [ "squirrel" ],
        "darwin": [ "zip" ],
        "linux": [ "deb","rpm" ]
      },
      "electronPackagerConfig": {
        "protocols":[
          {
            "protocol":"custom",
            "name":"custom",
            "schemes":"custom"
          }
        ]
      }
    }