This patch adds a section to the documentation on the late binding

This patch adds a section to the documentation on the late binding
feature for PCI devices. It provides some examples (mostly stolen from
the e-mail which accompanied the late-binding patch) of how to use the
sysfs attributes for late binding.

This patch was revised from the last documentation patch that I
submitted which included this and some documentation on the permissive
flag. I've divided the two sections up and I'd like this one considered
for acceptance now while I revise the permissive flag code.

Signed-off-by: Ryan Wilson <hap9@epoch.ncsc.mil>