Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

beep(1): Initial version of utility to create terminal beep via soundcard.

Reviewed by: imp@, emaste@ and pstef@
Differential Revision: https://reviews.freebsd.org/D32672
MFC after: 1 week
Sponsored by: NVIDIA Networking