This tries to add information about when each option was added. It goes
back to version 183.
The version info is included from a separate file to allow generating it,
which would allow more control on the formatting of the final output.
In D-Bus, clients connect to a bus (the usual case), or use direct
questions to each other (the unusual case). A bus is a program one can
connect to and implemented by dbus-daemon or dbus-broker. HOwever,
busses never connect between each other, that doesn't exist. Hence don't
claim so.
This is probably confusion about the fact that sd-bus calls D-Bus
connection objects just "sd_bus" for simplicity, given they are used in
99% of the cases to connect to a bus — only in exceptional cases they
are used for direct connections between peers without involving a bus.
Follow-up for b7bb58ef70