Bug 34743: Fix POD description

Bug 34743: Fix POD description

Currently --expiration-from-today has the same definition as --update-expiration. The description has now been updated to reflect the fact that it will set the date from today, and not the patron's enrollment date

Test plan:
Look at the patch file and confirm that the POD now mentions today's date rather than the patron's enrollment date

Signed-off-by: Laura Escamilla <laura.escamilla@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>