Introduction:

https://people.debian.org/~elbrus/debconf/Debconf2016_dbc_bof_intro.odp

mongodb (zigo) needs the questions, not necessarily the handling

dh --with dbconfig-common

Put some information on how to use dbconfig-common into the Debian
wiki, like for example done for Apache 2.4
  https://wiki.debian.org/Apache/PackagingFor24