stderrthreshold: fix flag comment

The code is so that the -stderrthreshold gets ignored when
-alsologtostderr=true.

klog.go

@@ -415,7 +415,7 @@ func init() {
 	logging.stderrThreshold = severityValue{
 		Severity: severity.ErrorLog, // Default stderrThreshold is ERROR.
 	}
-	commandLine.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr when writing to files and stderr (no effect when -logtostderr=true or -alsologtostderr=false)")
+	commandLine.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr when writing to files and stderr (no effect when -logtostderr=true or -alsologtostderr=true)")
 	commandLine.Var(&logging.vmodule, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
 	commandLine.Var(&logging.traceLocation, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")