psql: Add verbose option (+) for \dX command

Hi,

While I was reviewing another patch I noticed that we don't have the
verbose option(+) on \dX command to get extended statistics comments.

Althrought comments can be obtained using obj_description() perhaps it
can be useful to have a verbose option on \dX to get this information.

Thoughts?

--
Matheus Alcantara
EDB: https://www.enterprisedb.com