Documentation is overall ok, I will merge this pull request
But please do not dig down to this kind of description. It just repeats what 'disk_successes' mean, and this is useless.
None really knows what does it mean 'number of times when the command was succeeded in disk' - does it count cache write-through, does it count cache operation at all?

And so on and so on, please write documentation like you are trying to describe this system to your 10 years old sister, who already knows computers.