[Theme] More complete example of JSON file for syntax highlighting

### Description

More complete example of JSON file for syntax highlighting

### Use case/motivation

The example JSON file for syntax highlighting is the one provided by the [json.org](https://json.org/example.html) site.

This example only contains strings, object and array.

```json
{
"glossary": {
"title": "example glossary",
"GlossDiv": {
"title": "S",
"GlossList": {
"GlossEntry": {
"ID": "SGML",
"SortAs": "SGML",
"GlossTerm": "Standard Generalized Markup Language",
"Acronym": "SGML",
"Abbrev": "ISO 8879:1986",
"GlossDef": {
"para": "A meta-markup language, used to create markup languages such as DocBook.",
"GlossSeeAlso": [
"GML",
"XML"
]
},
"GlossSee": "markup"
}
}
}
}
}
```
This is not enough to set syntax highlighting
Can you provide a more complete example like this:

```json
{
"object": {
"array": [
{ "value": "first" },
{ "value": "second" }
],
"bool_false": false,
"bool_true": true,
"char": "a",
"encoding": "\uD83D\uDE10",
'error': 'error',
"exponential": 1E2,
"exponent": 1e2,
"float": 1.0,
"integer": 1,
"null": null,
"regex": "/.HTML/",
"string": "Lorem ipsum",
"url": "http://example.com",
"void": ""
}
}
```
The syntax highlighting example is not intended to represent a real case, but only to help create themes. Real cases are never complete enough

Expected result:

I don't know if adding an error in the example is relevant :man_shrugging:

### Related issues

_No response_

### Are you willing to submit a pull request?

No

### Code of Conduct

Yes