How to query posts based on categories in Sanity.io

    name: 'categories',
      title: 'Categories',
      type: 'array',
      of: [{ type: 'reference', to: { type: 'category' } }],
    },

  name: 'category',
  title: 'Category',
  type: 'document',
  fields: [
    {
      name: 'title',
      title: 'Title',
      type: 'string',
    },
    {
      name: 'description',
      title: 'Description',
      type: 'text',
    },
  ],

*[_type == "post" && references(*[ title == "Front-end"]._id)]{...}

*[_type == "category"]

*[_type == "category"]{..., reference->}