Add setup information for the examples

The examples currently lack the setup information which makes hard to adopt with similar boards. We should add a respective README.md for each one, preferably in the same format. I'm thinking:

# <name of the example>

<a small description>

## Pinmap

<pinout image of the board (find it from the internet)>

<markdown table of pins>

## Wiring

<some image,text or mermaid diagram>

## Notes

<other related info>

For example:

# ESP32 no-std demo

This example showcases .....

## Pinmap

| Function      | ESP32 pin | Notes                                |
| ------------- | --------- | ------------------------------------ |
| LCD backlight | `GPIO4`   | Set high to enable backlight         |
| SPI SCK       | `GPIO18`  | ST7789 clock                         |
| SPI MOSI      | `GPIO19`  | ST7789 data                          |

## Wiring

```mermaid
flowchart LR
etc
```

## Notes

Pls set your display size

Checklist

• epd-waveshare-demo (ping @tchmnn in case they want to do this :))
• esp32-no-std-demo
• esp32-std-demo