Update changelog.md with 1.22.0 release notes.
Update changelog.md with 1.22.0 release notes.

jonvestal/open-kilda,telstra/open-kilda,jonvestal/open-kilda,jonvestal/open-kilda,telstra/open-kilda,telstra/open-kilda,telstra/open-kilda,jonvestal/open-kilda,telstra/open-kilda,jonvestal/open-kilda,telstra/open-kilda,telstra/open-kilda