d/neopi.1: fix hyphen used as minus sign

Let's fix these lintian reports:

I: neopi: hyphen-used-as-minus-sign usr/share/man/man1/neopi.1.gz:95
I: neopi: hyphen-used-as-minus-sign usr/share/man/man1/neopi.1.gz:97
I: neopi: hyphen-used-as-minus-sign usr/share/man/man1/neopi.1.gz:99

Signed-off-by: Arturo Borrero Gonzalez <aborrero@cica.es>