docs: update roadmap document with v2.2 release changes (argoproj#8089)

Signed-off-by: Alexander Matyushentsev <AMatyushentsev@gmail.com>

Bump version to 2.2.2

Bump version to 2.2.1

Bump version to 2.2.0

Bump version to 2.1.8

Bump version to 2.1.7

Bump version to 2.2.0-rc1

Bump version to 2.1.6

Bump version to 2.1.5

Bump version to 2.1.4