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!

Start by reviewing the README's existing usage examples and how fenced JavaScript blocks are represented in Snarkdown output. Check the PrismJS integration approach, then add a README example using the requested markdown input and both tools; done means the example clearly shows the converted, highlighted result.

Written by the indexing model from the issue text.