Docs: Update CLI ref for 3.0/3.1

[Thraka]

CLI reference hasn't been updated for 3.0. This should be updated.

This issue applies to all dotnet command articles.

---

Document Details

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

• ID: 0ba6c9b5-64cb-1dc6-21d0-ad8f0a1185fe
• Version Independent ID: 0f6c658c-b477-2d2c-2a9a-d74f6ae38d3f
• Content: dotnet command - .NET Core CLI
• Content Source: docs/core/tools/dotnet.md
• Product: dotnet-core
• Technology: dotnet-cli
• GitHub Login: @mairaw
• Microsoft Alias: mairaw

[Thraka]

Per request, moving to @mairaw since she is doing the 2.2 CLI ref

[jbe2277]

Please, update the reference to include .NET Core 3.1 as well.