This adds release notes covering some of the main fixes and features in

this release (new diff metadata, compatibility fixes, fixes for

crashes). It also fixes an incorrect version shown in the 4.0.5 release

notes.
Docker building has been updated to explicitly create x86 images, rather

than native architecture images.
The required minimum version of Django Evolution has been updated to

2.1.4.

Built the release notes. Checked for build and spelling errors.
Tested building new Docker images and verified the architecture.