docs: specify database and user role when running psql

[langfingaz]

During the steps to re-import a PostgreSQL dump, the tool psql is used twice.

On first usage, the database and user role are specified:

recipes/docs/system/updating.md

Line 80 in 5129ef7

cat ~/tandoor.sql | sudo docker exec -i {{database_container}} psql postgres -U {{djangouser}}

At the second time, psql is run without any arguments:

recipes/docs/system/updating.md

Line 84 in 5129ef7

docker exec -it {{database_container}} psql

This gave me the following error:

psql: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: FATAL:  role "root" does not exist

If I am not wrong, we should specify the database and user role here, as well. This is fixed by this merge request:

docker exec -it {{database_container}} psql postgres -U {{djangouser}}

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Edit: I noticed this during my upgrade from postgres:11-alpine to postgres:16-alpine

[vabene1111]

yes that makes sense, thank you very much