Add some examples how to configure QuasiQuotation syntax highlighting?

First of all, I'm sorry if this is too much unrelated to `language-haskell` itself, but I was wondering if you could provide some examples (or at least links to some external documentation) how exactly can I configure the newly added logic that allows syntax highlighting for _quasiquotes_? Why I'm asking for this - I'm really happy with this _VSCode_ extension, but I have zero experience how it works under the hood. I can imagine that most of people would use this highlighting stuff to some common use-cases, such as to highlight _quasiquotations_ used to build _regular expressions_ or string interpolators, such as:

```haskell
let regex = [re|^\h*-}|\w+\h*-}|^--|]
let interpolated = [i|Hello, #{userName user}|]
```

I have no idea how much work is to configure the syntax highlighting for this, but maybe it would be worth it to more promote this feature in documentation with few examples?

Start with the VSCode extension's existing quasiquotation syntax-highlighting configuration and documentation, then identify where user-facing examples or external links belong. Document configuration examples for regular-expression and string-interpolation quasiquotes, and consider the work done when users can follow the documentation to configure both cases.

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