Please see git logs for detailed change log.
This file just contains highlight.

Changes Prior to release 3.1.1
   -    Multiple fixes for new --grow levels including fixes for
	serious data corruption problems.
   -    Change default metadata to v1.1
   -    Change default chunk size to 512K
   -    Change default bitmap chunk size to 64Meg
   -    When --re-add is used, don't fall back to
	--add if --re-add fails as this can destroy data.

Changes Prior to release 3.1
   -    Support --grow to change the layout of RAID4/5/6
   -    Support --grow to change the chunksize of raid 4/5/6
   -    Support --grow to change level from RAID1 -> RAID5 -> RAID6 and
        back.
   -    Support --grow to reduce the number of devices in RAID4/5/6.
   -    Support restart of these grow options which assembling an array 
	which is partially grown.
   -    Assorted tests of this code, and of different RAID6 layouts.
	
Changes Prior to release 3.0.3
   -    Improvements for creating arrays giving just a name, like 'foo',
	rather than the full '/dev/md/foo'.
   -    Improvements for assembling member arrays of containers.
   -    Improvements to test suite
   -    Add option to change increment for RebuildNN messages reported
	by "mdadm --monitor"
   -    Improvements to mdmon 'hand-over' from initrd to final root.
   -    Handle merging of devices that have left an IMSM array and are
	being re-incorporated.
   -    Add missing space in "--detail --brief" output.
	
Changes Prior to release 3.0.2
   -    Fix crash when hosthost is not set, as often happens in
	early boot.

Changes Prior to release 3.0.1
   -    Fix various segfaults
   -    Fixed for --examine with containers
   -    Lots of other little fixes.
	
Changes Prior to release 3.0
   -    Support for externally managed metadata, specifically DDF and IMSM.
   -    Depend on udev to create entries in /dev, rather than creating them
	ourselves.
   -    remove --auto-update-home-hosts
   -    new config file line "auto"
   -    new "<ignore>" and "any" options for "homehost"
   -    numerous bug fixes and minor enhancements.