There's no man page, but it'll tell you:
Actually, there is a man page, cf.1, which can be formatted using nroff
-man as usual for Unix man pages.
This version of cf is newer than the one in aux/cf/ of the Bro distribution
(as you well know!, since you are the one who contributed the additions),
but will be included in the next Bro release as aux/cf-1.1/ .