Update README.md for ArduinoJSON 6

[mrengineer7777]

ESPAsyncWebServer library supports AJ6, but the examples in the readme have not been updated.

See https://arduinojson.org/v6/doc/upgrade/. There may be other changes necessary for AJ6.

[chess-levin]

I'm trying to use your simple JSON response example with ArduinoJson 6.1 and can't compile. Is there a work around for this deprecation-issue ?

Ok, that callback works for me. I've used https://arduinojson.org/v6/doc/upgrade/ to find my solution.

void handleGetSensorInfo(AsyncWebServerRequest *request) {
	PRINTSLN("handleGetSensorInfo()");

	AsyncResponseStream *response = request->beginResponseStream(MIMETYPE_JSON);
	DynamicJsonDocument doc(128);

    doc[F("luxMeterOk")] = isLuxMeterOk();
	doc[F("lux")] = getLastLuxMeasuremen();
	doc[F("luxThresCount")] = getLuxThresCounter();
	doc[F("pir1")] = isIsPirOn(1);
	doc[F("pir2")] = isIsPirOn(2);

	serializeJsonPretty(doc, *response);
	request->send(response);
}

[mrengineer7777]

@chess-levin Correct. You want to switch from JsonBuffer to JsonDocument. The dynamic part has been deprecated. DynamicJsonDocument is actually a fixed size. The only difference between Static and Dynamic is where the buffer is allocated.

See https://arduinojson.org/ "Fixed Memory Allocation".