📝 Add documentation on how to use the Django ORM inside FastAPI

[patrick91]

• Add initial documentation for using the Django ORM
• Add async example

[tiangolo]

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[tiangolo]

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[YuriiMotov]

I think it would be better to move this guide to "How To - Recipes" section.

Also, using global object to access DB session is not a good practice. It should be at least moved to dependency to allow it to be overridden in tests.

Overall, I like the manner of presentation, and I find this guide useful.