[AD] Timer doc suggestion

[Jörg Rüppel <asharky@xxxxxxxxxx>]

Hi there,

here's an excerpt from 3.9.39 Timer Documentation:

"Allegro can set up several virtual timer functions, all going at different 
speeds, and will constantly reprogram the clock to make sure they are all 
called at the correct times."

Could someone who knows about how Allegros timers work on all the different 
platforms update the docs here? I don't think the Linux version programs the 
clock ;-P

Just curious how the timer backends work and how exact they are.

Thanks
Jörg