Document DRBD dynamic resync params in man pages

Also, remove some spurious spaces in the documentation of other options
and uniform the style of the disk parameters descriptions, by
terminating them with a period and adding the measurement unit in square
brackets after the description.

Signed-off-by: Andrea Spadaccini <spadaccio@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>