find: Logic nit in man page.

Arguments follow primaries, not the other way around.

MFC after: 1 week
Sponsored by: Klara, Inc.

Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D38173

(cherry picked from commit 14ebab25e1231decd80a64194e9028a9ada8d6e6)