hub-workflow-status: Documentation: Mention possible values for STATE…

… and CONCLUSION

Source: github/rest-api-description#1634

bin/hub-workflow-status

@@ -57,9 +57,13 @@ HELPDESCRIPTION
 			revision of the tracked remote branch.
     --latest|-l		Only print / consider the last status.
     --is STATE		Only print if one / the status is STATE; else fail.
+			Can be one of: "queued", "in_progress", or "completed".
     --concluded CONCLUSION
 			Only print if one / the workflow concluded with
 			CONCLUSION; else fail.
+			Can be one of the "success", "failure", "neutral",
+			"cancelled", "skipped", "timed_out", or
+			"action_required".
     --print-all		A match of STATE / CONCLUSION only determines the exit
 			status but does not drop non-matching workflows from the
 			output.