Bug 14545: Typo in help file (stage-marc-import.tt)

Bug 14545: Typo in help file (stage-marc-import.tt)

Typo found in stage-marc-import.tt file for Koha help in 3.20

Test plan:
1) Go to url 'koha-tmpl/intranet-tmpl/prog/en/modules/help/tools/stage-marc-import.tt:28' and check the typo "precendence" or go to Tools > Stage MARC records for import and open up the help
2) Apply the patch
3) Repeat step 1 and check if the typo is fixed.

Sponsored-by: Universidad de El Salvador
Signed-off-by: Nick Clemens <nick@quecheelibrary.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>