✨ Support title option

[YuriiMotov]

This PR adds support for title config option:

{* docs_src/app/internal/admin.py title["app/internal/admin.py"] *}

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@tiangolo edit: Quotes are optional. let's make quotes required, as a dict.

Note: Current implementation doesn't allow using ] in title text. Do we need to handle this?

[tiangolo]

Awesome, thank you! 🙌

I made the title quotes required to prevent us from skipping them, to start more strict now that we can and relax only if necessary (it's harder to start relaxed and then make it more strict).

I think for now it's fine to not support [ and ] in the title text, I think we have never used it.