Update error message for --preview-window

src/options.go

@@ -1200,7 +1200,7 @@ func parseOptions(opts *Options, allArgs []string) {
 			opts.Preview.command = ""
 		case "--preview-window":
 			parsePreviewWindow(&opts.Preview,
-				nextString(allArgs, &i, "preview window layout required: [up|down|left|right][:SIZE[%]][:wrap][:hidden]"))
+				nextString(allArgs, &i, "preview window layout required: [up|down|left|right][:SIZE[%]][:noborder][:wrap][:hidden]"))
 		case "--height":
 			opts.Height = parseHeight(nextString(allArgs, &i, "height required: HEIGHT[%]"))
 		case "--min-height":