docs: Consistently format each form of an option on a separate line.

docs: Consistently format each form of an option on a separate line.

Most options were formatted like this in the manpage:

    -o ARGUMENT
    --option ARGUMENT

but a few were formatted like this:

    -o ARGUMENT | --option ARGUMENT

or even as:

    -o, --option ARGUMENT

The former seems least confusing to me, so switch all of the documentation
to this format.

Signed-off-by: Ben Pfaff <blp@nicira.com>