Update/revise/move/remove "How queries work" section

If you can given an example execution happening from C# to the database back to C#, that would be nice. Because even though I read this, I don't know what it means to cache as mentioned in 1a. If I ran `Author.Books.ToList()` twice, do two executions run or not? An example may have answered this for me.

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#### Document Details

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* ID: 3208b215-1bac-c110-12f4-e1a6b448fdaf
* Version Independent ID: 3f6fb56f-0a79-8861-f8c4-ea5969a9aff5
* Content: [How Queries Work - EF Core](https://docs.microsoft.com/en-us/ef/core/querying/overview)
* Content Source: [entity-framework/core/querying/overview.md](https://github.com/aspnet/EntityFramework.Docs/blob/master/entity-framework/core/querying/overview.md)
* Product: **entity-framework**
* Technology: **entity-framework-core**
* GitHub Login: @rowanmiller
* Microsoft Alias: **divega**