Reformat PostgreSQL documentation…

…because @mirabilos is too 1337 to stick to basic rules.

docs/admin/02_psql.rst

+Installing BiscuIT with PostgreSQL backend
+=========================================
+
+PostgreSQL is the preferred database backend for BiscuIT. You should use it
+in every production setup and use SQLite only for testing.
+
+
+Install the PostgreSQL server
+-----------------------------
+
+On Debian, install the postgresql server package with::
+
+  sudo apt install postgresql
+
+
+Create a database and user
+--------------------------
+
+On Debian, you can use the following commands to create the database and a
+user who owns it::
+
+  sudo -u postgres createuser -D -P -R -S biscuit
+  sudo -u postgres createdb -E UTF-8 -O biscuit -T template0 -l C.UTF-8 biscuit
+
+When asked for the database user password, choose a secure, preferrably
+random, password. You can generate one using the pwgen utility if you like::
+
+  pwgen 16 1
+
+
+Configure BiscuIT to use PostgreSQL
+-----------------------------------
+
+Fill in the configuration under `/etc/biscuit/*.toml`::
+
+  [default.database]
+  engine = "django.db.backends.postgresql"
+  name = "biscuit"
+  username = "biscuit"
+  password = "Y0urV3ryR4nd0mP4ssw0rd"
+
+Don't forget to run the migrations, like described in the basic setup guide.

docs/admin/02_psql.txt

-Instaling BiscuIT with PostgreSQL backend
-─────────────────────────────────────────
-
-• Install PostgreSQL, for example with:
-
-	sudo apt install postgresql-contrib
-
-• Create a database role with login permissions:
-
-	sudo -u postgres createuser -D -P -R -S biscuit
-    <username>─────────────────────────────────────┘
-
-  This step asks interactively for the password to set.
-
-• Create a database belonging to the new user:
-
-	sudo -u postgres createdb -E UTF-8 -O biscuit -T template0 -l C.UTF-8 biscuit
-    <username>───────────────────────────────────┘                               │
-    <databasename>───────────────────────────────────────────────────────────────┘
-
-• Fill in the configuration under /etc/biscuit/*.toml:
-
-	[default.database]
-	engine = "django.db.backends.postgresql"
-	name = "biscuit"
-	username = "biscuit"
-	password = "biscuit"
-
-• Run the migrations.