Add ChakraCore documentation

[dustinsoftware]

Fixes #540

Startup.cs in tutorial code was incorrectly using indentation with spaces, this PR fixes that as well

[Taritsyn]

Hello, Dustin!

It seems to me, that in example for ASP.NET Core should be mentioned about the JavaScriptEngineSwitcher.Extensions.MsDependencyInjection package, because it greatly facilitates registration of JS engines:

…
using JavaScriptEngineSwitcher.ChakraCore;
using JavaScriptEngineSwitcher.Extensions.MsDependencyInjection;
…

namespace ReactDemo
{
	public class Startup
	{
		…

		public void ConfigureServices(IServiceCollection services)
		{
			…
			services.AddJsEngineSwitcher(options =>
				options.DefaultEngineName = ChakraCoreJsEngine.EngineName
			)
				.AddChakraCore()
				;
			…
		}

		…
		}
	}
}

In addition, you can give links to the “Registration of JS engines” and “JS Engine Switcher: ChakraCore” sections of JavaScript Engine Switcher documentation.

[dustinsoftware]

Thanks @Taritsyn! I'll update the docs.

[Daniel15]

Thanks for working on this, @dustinsoftware. I appreciate it!