Bug 25755: (QA follow-up) Clarify POD and parameters

Bug 25755: (QA follow-up) Clarify POD and parameters

This patch removes a FIXME that signified possible future work and also
updates the POD and optional parameters to more clearly specify their
function.

Signed-off-by: Kathleen Milne <kathleen.milne@cne-siar.gov.uk>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>