File Uploads topic enhancements and Container issue

28K PV
---
Additional issues

- [ ] File Signature magic numbers #18012

It won't be possible to address one of the issues in the updates for https://github.com/aspnet/AspNetCore.Docs/issues/10214.

The following opportunities remain:

## High Priority

* [ ] Include `using` statements as comments in the in-text code examples and at the tops of methods/classes shown from the sample app.
* [ ] There's no example for handling file chunking; for example to resume large file uploads when users are in remote areas with flaky Internet. See :point_right: https://github.com/aspnet/AspNetCore.Docs/issues/12285#issuecomment-541736994

## Medium Priority

* [ ] Apache/Nginx server limits configuration
* [ ] The article doesn't mention the [FileExtensions] attribute, which can be used to restrict what files can be uploaded. #13905
* [ ] Are these instructions Core 3.0 Web API Compatible? #15716

## Low Priority

- [ ] There's no example for Byte Range when downloading.
- [ ] Can you provide an example of using JSON plus IFormFile? #18290
- [ ] Q: What is the benefit of streaming? #18070
- [ ] Unity asset bundles not working #19235

## Hold for future engineering work

* [ ] Background queued file processing with `QueueBackgroundWorkItem` is on the backlog :point_right: https://github.com/aspnet/Extensions/issues/805

**KEEP AN :eye: ON https://github.com/aspnet/AspNetCore/issues/2711**

---
#### Document Details

⚠ *Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.*

* ID: 9a5cfa38-0e6c-4346-dafc-84ea5c513fcf
* Version Independent ID: c6787f0f-3e9a-6efb-0e6e-5ccb957d3f4a
* Content: [File uploads in ASP.NET Core](https://docs.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-2.2#feedback)
* Content Source: [aspnetcore/mvc/models/file-uploads.md](https://github.com/aspnet/AspNetCore.Docs/blob/master/aspnetcore/mvc/models/file-uploads.md)
* Product: **aspnet-core**
* Technology: **aspnetcore-mvc**
* GitHub Login: @ardalis
* Microsoft Alias: **riande**