Update README.md

[gracegtaylor]

Add additional pre-requisites.

[huguesv]

Converter requires .NET Core 3.1 Runtime, not .NET 5. That can be installed via VS installer. They also need .NET Desktop development workload, and Visual Studio extension development workload.

[mariorodeghiero]

@gracegtaylor Just you know the error that I talked. I received this error when I tried, maybe could be because I was using my Linux. After I update to the 5.x version the build works properly.

theme-converter-for-vs/ThemeConverter/ThemeConverter on  main [?] via .NET 3.1.412 took 4s 
➜ sudo dotnet build ThemeConverter.csproj
[sudo] password for rodeghiero: 

Welcome to .NET Core 3.1!
---------------------
SDK Version: 3.1.412

Telemetry
---------
The .NET Core tools collect usage data in order to help us improve your experience. It is collected by Microsoft and shared with the community. You can opt-out of telemetry by setting the DOTNET_CLI_TELEMETRY_OPTOUT environment variable to '1' or 'true' using your favorite shell.

Read more about .NET Core CLI Tools telemetry: https://aka.ms/dotnet-cli-telemetry

----------------
Explore documentation: https://aka.ms/dotnet-docs
Report issues and find source on GitHub: https://github.com/dotnet/core
Find out what's new: https://aka.ms/dotnet-whats-new
Learn about the installed HTTPS developer cert: https://aka.ms/aspnet-core-https
Use 'dotnet --help' to see available commands or visit: https://aka.ms/dotnet-cli-docs
Write your first app: https://aka.ms/first-net-core-app
--------------------------------------------------------------------------------------
Microsoft (R) Build Engine version 16.7.2+b60ddb6f4 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  Restored /home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj (in 1.69 sec).
Program.cs(213,51): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]
Program.cs(213,89): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]
Program.cs(397,36): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]
Program.cs(402,36): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]

Build FAILED.

Program.cs(213,51): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]
Program.cs(213,89): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]
Program.cs(397,36): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]
Program.cs(402,36): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/rodeghiero/experiments/theme-converter-for-vs/ThemeConverter/ThemeConverter/ThemeConverter.csproj]
    0 Warning(s)
    4 Error(s)

Time Elapsed 00:00:03.32

Now I will test on my Windows.

[gracegtaylor]

@mariorodeghiero Thank you for sharing the context, and for trying the tool! The main use case is Windows for the initial iteration, and Linux was not scoped yet. We are continually improving the conversion process, and we're looking forward to hearing more feedback.