The "reflog selector" format changes based on a series of
heuristics, and that applies equally to both stock "log -g"
output, as well as "--format=%gd". The documentation for
"%gd" doesn't cover this. Let's mention the multiple formats
and refer the user back to the "-g" section for the complete
rules.
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>