Add usage example with PrismJS

I'd like to request a usage example that takes markdown which includes JS like this example:
```
## Example
```js
console.log(1)
　```
```
And then convert with both Snarkdown + PrismJS.

I've tried many things but I'm failing to succeed in this task! 😅

I think the community at large will greatly benefit from an example like this in the readme!