DSMR hardware example

**Describe the problem you have/What new integration you would like**

A complete example of hardware that can be used with the esphome dsmr implementation

**Please describe your use case for this integration and alternatives you've tried:**

I am having difficulties finding the correct way to wire an esp8266/esp32 to the p1 port so that it can be used with esphome.
Are there any more schematics/tutorials available that are known to work with esphome?

**Additional context**

Start by reviewing the ESPHome DSMR implementation and the P1-port wiring problem described in the issue. Document a known ESP8266 or ESP32 hardware setup, including schematics or tutorial steps; done means the complete example can be used with the ESPHome DSMR implementation.

Written by the indexing model from the issue text.