doc: activemq: lokkit and service replaced by firewall-cmd and systemctl
Signed-off-by: Lokesh Mandvekar <lsm5@redhat.com>

lokkit no longer works when firewallD is active. use of firewall-cmd is
recommended.

'service activemq start' forwards the request to 'systemctl', so it's been
replaced with the latter

modified:   documentation/install_origin_manually.md