Update documentation about manual setup of PostgreSQL

1. Remove mentioning of version from which PostgreSQL is supported ( this was introduced
so many years ago so no really find version which does not support it)
2. Explicitly state requirements of PostgreSQL setup

docs/Installing.asciidoc

@@ -387,15 +387,11 @@ httpsonly = 0
 [[database]]
 === Database
 
-Since version _4.5.1512500474.437cc1c7_ of openQA, PostgreSQL is used as the
-database.
-
-To configure access to the database in openQA, edit `/etc/openqa/database.ini`
-and change the settings in the `[production]` section.
-
-The `dsn` value format technically depends on the database type and is
-documented for PostgreSQL at
-https://metacpan.org/pod/DBD::Pg#DBI-Class-Methods[DBD::Pg]
+PostgreSQL used by openQA suppose to have database with name `openqa` and
+`geekotest` user as owner of this database. Automatic setup of freshly installed
+PostgreSQL instance can be done using https://github.com/os-autoinst/openQA/blob/master/script/setup-db[this script].
+Connection to database configured in `/etc/openqa/database.ini` in `[production]`
+section. More info about `dsn` value format you can find in https://metacpan.org/pod/DBD::Pg#DBI-Class-Methods[DBD::Pg].
 
 ==== Example for connecting to local PostgreSQL database