856ca51a23
This was only mentioned in the description of the text/label, which are marked as being in quotes in the synopsis, which can cause confusion (as witnessed on IRC). Also separate the literal and NULL cases in the parameter list, per suggestion from Tom Lane. Also add an example of dropping a security label. Dagfinn Ilmari Mannsåker, with some tweaks by me Discussion: https://postgr.es/m/87sffqk4zp.fsf@wibble.ilmari.org