Update freebsd.md: update rc.d script, use the standard rc functions for stop and status.

Open username-removed-555845 requested to merge c0by/gitlab-ci-multi-runner:patch-1 into master

Status: Split the 'run' argument to command_args, this fixes the 'WARNING: no shebang line in /usr/local/bin/gitlab-ci-multi-runner' on status.

Stop: With inbuilt rc stop, rc will poll the pid until it's dead