md: remove doubled description for sync_max, merging it within sync_min/sync_max
md: remove doubled description for sync_max, merging it within sync_min/sync_max

After last md.txt edits for sync_min/max, sync_max description became
doubled. Removing 1st copy, merging details into common
sync_min/sync_max section.

Signed-off-by: Roman Ovchinnikov <a4536ccde6741af8e48c9e93bd72d10cf78d76ba@gmail.com>
Signed-off-by: NeilBrown <1c00aa603bb92d594c03cff60ecf8e63b2a5bcb1@suse.de>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs