Add file to help usage

Author: jwilder

main.go

@@ -217,7 +217,7 @@ func main() {
 	flag.Var(&stderrTailFlag, "stderr", "Tails a file to stderr. Can be passed multiple times")
 	flag.StringVar(&delimsFlag, "delims", "", `template tag delimiters. default "{{":"}}" `)
 	flag.Var(&headersFlag, "wait-http-header", "HTTP headers, colon separated. e.g \"Accept-Encoding: gzip\". Can be passed multiple times")
-	flag.Var(&waitFlag, "wait", "Host (tcp/tcp4/tcp6/http/https/unix) to wait for before this container starts. Can be passed multiple times. e.g. tcp://db:5432")
+	flag.Var(&waitFlag, "wait", "Host (tcp/tcp4/tcp6/http/https/unix/file) to wait for before this container starts. Can be passed multiple times. e.g. tcp://db:5432")
 	flag.DurationVar(&waitTimeoutFlag, "timeout", 10*time.Second, "Host wait timeout")
 	flag.DurationVar(&waitRetryInterval, "wait-retry-interval", defaultWaitRetryInterval, "Duration to wait before retrying")