Bug 25552: (QA follow-up) Improve claim_returned POD

Bug 25552: (QA follow-up) Improve claim_returned POD

The POD for the Koha::Checkout->claim_returned method was somewhat
lacking; This patch attempts to explain what the code appears to
achieve.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 8c09123197bc4bf8997ba4cd1b727c80eef9077e)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 446e2a5e32a3ac3bb6735f59ba393d82d04e9ba9)

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>