Add alternative installation/build method in README

[Dhritishman Sarmah]

For people who have never used VS or C# or .NET (like me ;-;), it would be better to add some more alternatives and direct build instructions:

• Install .NET 6 (same link given on README)
• open terminal/cmd
• cd path\to\Chess-Challenge\Chess-Challenge.csproj
• dotnet run

Now you can use any code editor.

[Lisa Magdalena Riedler]

ah wow thank you. I was trying stuff with manually running msbuild, which didn't work.

honestly, that should be in the Readme.

[Satvik Srinivas]

Thank you this was very helpful!

[Sebastian Lague]

Thanks for sharing these instructions. I've added a link to this in the readme.