Fish polish translation plural descriptor string

According to online sources [0], Polish is a language with complex
plural conditions. Fix the current translation file to reflect this.

0: https://docs.translatehouse.org/projects/localization-guide/en/latest/l10n/pluralforms.html



Suggested-by: rail <rail01@protonmail.com>
Signed-off-by: lymkwi <lymkwi@vulpinecitrus.info>