如何将EF核心迁移添加到.net核心2类库？

dotnet --version
dotnet ef --version

dotnet new classlib -n MyLibrary

cd MyLibrary

dotnet add package Microsoft.EntityFrameworkCore

using Microsoft.EntityFrameworkCore;

namespace MyLibrary
{
    public class MyDbContext : DbContext
    {
        public MyDbContext(DbContextOptions<MyDbContext> options) : base(options)
        {
        }

        // Define your entity sets here
        // public DbSet<MyEntity> MyEntities { get; set; }
    }
}

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace MyLibrary
{
    public static class Startup
    {
        public static void ConfigureServices(IServiceCollection services, string connectionString)
        {
            services.AddDbContext<MyDbContext>(options =>
                options.UseSqlServer(connectionString));
        }
    }
}

dotnet build
dotnet pack