Package: postgis Version: 2.2.2+dfsg-3 Severity: wishlist File: /usr/share/doc/postgis/README.Debian
We read
To install the PostGIS extension as well as its topology extension
in a specific database, you need to run the following SQL commands
from your database prompt:
CREATE EXTENSION postgis;
CREATE EXTENSION postgis_topology; -- optional
Mention that you need to
su - -s /bin/bash postgres
psql some_database
and then enter the commands. Else you will get an error.

