Upgrade to 21.3 release.
Add tzdata dependancy, remove e2fsprogs-extra dependancy.
Add logrotate configuration file.
Add cloud-init-hotplugd init.d script and simple daemon for new network
hotplug functionality in this release.
Remove some more unnecessary (doc) files from package.
Update README.Alpine to add known issue (and solution) for SSH access with
locked user accounts, and to detail how to use hotplug functionality.