Update for Dotnet core 3.0

[Paul-Dempsey]

Needs maintenance to bring up to netcore 3.0

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Document Details

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• ID: 0b952f8a-18e1-4843-0741-6ca877fb303a
• Version Independent ID: d80dfb96-bc86-a960-abec-255dd907d04d
• Content: dotnet new command - .NET Core CLI
• Content Source: docs/core/tools/dotnet-new.md
• Product: dotnet-core
• Technology: dotnet-cli
• GitHub Login: @mairaw
• Microsoft Alias: mairaw

[Paul-Dempsey]

never mind -- I see this is a dupe of #9893, but that issue looks like it has been getting kicked down the road for many months.

[mairaw]

And I already have a PR in progress. It's just complicated because I'm redoing the entire article and lots of things going on. But I plan on finishing it soon.

PR #14356