Container issue: Host ASP.NET Core on Linux with Nginx

This is the container issue for this doc. If you PR this doc and don't fix all the issues, open the issues you fix and close against that.

PU issues:
- [ ] Should explain how testCert.crt/testCert.key can be generated #17724
- [ ] https://github.com/dotnet/AspNetCore.Docs/issues/14005
- [ ] Deploy to subdirectory #15464

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#### Document Details

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* ID: dcdd2c35-bf2b-2673-d150-303a8aaa54d2
* Version Independent ID: 815fe034-c9fc-aee3-a8b5-f2e860b30302
* Content: [Host ASP.NET Core on Linux with Nginx](https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/linux-nginx?view=aspnetcore-3.1#feedback)
* Content Source: [aspnetcore/host-and-deploy/linux-nginx.md](https://github.com/dotnet/AspNetCore.Docs/blob/master/aspnetcore/host-and-deploy/linux-nginx.md)
* Product: **aspnet-core**
* Technology: **aspnetcore-hostdeploy**
* GitHub Login: @Rick-Anderson
* Microsoft Alias: **riande**