bpd: document new control_port config
bpd: document new control_port config

SusannaMaria/beets,beetbox/beets,ibmibmibm/beets,sampsyo/beets,jackwilsdon/beets,shamangeorge/beets,beetbox/beets,beetbox/beets,SusannaMaria/beets,ibmibmibm/beets,jackwilsdon/beets,jackwilsdon/beets,ibmibmibm/beets,shamangeorge/beets,ibmibmibm/beets,shamangeorge/beets,beetbox/beets,sampsyo/beets,jackwilsdon/beets,SusannaMaria/beets,sampsyo/beets,sampsyo/beets,shamangeorge/beets,SusannaMaria/beets