Add indent on json stringify of examples

[kjuulh]

Hi, when doing examples if it is an object, or array and not a primitive type, the examples section isn't that useful, if a large object is shown, would it be possible to add indentation to the examples

https://github.com/redhat-developer/yaml-language-server/blob/220519da363544f659e63302fc31bdda0800c34c/src/languageservice/services/yamlHover.ts#L149

I'd be happy to add it if it is something we want =D

probably something like this:

s.schema.examples.forEach((example) => {
    markdownExamples.push(JSON.stringify(example, null, 4 / '\t'));
});

So instead of

```{"someObject": {"someProperty": "someValue"}}```

it would be

\```
{
    "someObject": {
         "someProperty": "someValue"
     }
}
\```

The ` formatting was a bit messed up.

If we were more ambitious we could probably even output it as yaml instead, which is more fitting to the package name =D

[gorkem]

I think this function can be helpful on how to implement this. I would be happy to review if you send a PR.