MLBEDSW-9438: Update release notes

- Add release notes for 4.0.0
- Add new config file additions to OPTIONS.MD description
- Add Regor debug CLI-options to OPTIONS.MD

Change-Id: Ie31a68e26076da401b9c24fca47579aa63d1faeb
Signed-off-by: Rickard Bolin <rickard.bolin@arm.com>