Is there any way to prefix a slug, ie category page for mens would be /category/mens?

{
  title: 'Slug',
  name: 'slug',
  type: 'slug',
  options: {
    source: doc => `/category/${doc.category}`
  }
}

{
  title: 'Slug',
  name: 'slug',
  type: 'slug',
  options: {
    source: doc => `/category/${doc.category}`,
    slugify: input => input
      .toLowerCase()
      .slice(0, 200)
  }
}