"public headers ("include") directory path for 'Guide' is invalid or not contained in the target" error

Hi, I have a problem with making a swift playgrounds app walkthrough. I followed the steps exactly and modified my Package.swift a bit (in the targets section):

.executableTarget(name: "App", dependencies: ["Guide"], path: "App"),

        .target(

            name: "Guide",

            path: "Guide",

            resources: [

            .process("Guide.tutorial"),

            ])

Now when I open the project in Playgrounds I get this error: public headers ("include") directory path for 'Guide' is invalid or not contained in the target

Any help would be appreciated.

Thanks