feat: add option for docker image rebuild (#878)

Adds option to rebuild local action docker images

Fixed up README due to missing flags after
PR #714 and #716

Signed-off-by: hackercat <me@hackerc.at>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

cmd/input.go

@@ -20,6 +20,7 @@ type Input struct {
 	platforms             []string
 	dryrun                bool
 	forcePull             bool
+	forceRebuild          bool
 	noOutput              bool
 	envfile               string
 	secretfile            string