newsyslog.conf(5): Accept human unit suffix in the size filed

MFC after: 1 week
Pull Request: https://github.com/freebsd/freebsd-src/pull/1505

(cherry picked from commit 1f78bbb5c415efefa782c1be7f9a2e4a5008903b)

newsyslog.conf(5): Remove duplicate word

Reported by: jlduran
Fixes: 1f78bbb5c415 newsyslog.conf(5): Accept human unit suffix in the size filed

(cherry picked from commit af2015b01f7e741125aeb4a04109cc42f988cf0f)