title: Arrange custom count in descending order using arel tables
body: <p>I have this table where I count the number of reservations for each product. I would like to have these counts in descending order. How could I go about it?</p>
  <pre><code>  Product.joins(
      Product.arel_table.join(Reservation.arel_table, Arel::Nodes::OuterJoin).on(
        Reservation.arel_table[:product_id].eq(Product.arel_table[:id])
      ).join_sources
    ).group(Product.arel_table[:id]).select(Product.arel_table[Arel.star],
    Reservation.arel_table[:id].count.as('res_count'))
  
  </code></pre>