Tweak NativeAOT repro instructions (dotnet#82018)

These work regardless where you copy of dotnet/runtime is checked out.

docs/workflow/building/coreclr/nativeaot.md

@@ -75,7 +75,7 @@ The workflow looks like this:
 * Build the repo using the Building instructions above
 * Open the ilc.sln solution described above. This solution contains the compiler, but also an unrelated project named "repro". This repro project is a small Hello World. You can place any piece of C# you would like to compile in it. Building the project will compile the source code into IL, but also generate a response file that is suitable to pass to the AOT compiler.
 * Make sure you set the solution configuration in VS to the configuration you just built (e.g. x64 Debug).
-* In the ILCompiler project properties, on the Debug tab, set the "Application arguments" to the generated response file. This will be a file such as "C:\runtime\artifacts\bin\repro\x64\Debug\compile-with-Release-libs.rsp". Prefix the path to the file with "@" to indicate this is a response file so that the "Application arguments" field looks like "@some\path\to\file.rsp".
+* In the ILCompiler project properties, on the Debug tab, set the "Application arguments" to `@$(ArtifactsBinDir)repro\$(TargetArchitecture)\$(Configuration)\compile-with-Release-libs.rsp`. The `@` at the front of the argument indicates that this is the path to the response file generated when "repro" was built. Adjust the "compile-with-Release-libs" part to "compile-with-Debug-libs" depending on how you built the libraries (the `-lc` argument to `build.cmd`). Visual Studio will expand the path to something like `@C:\runtime\artifacts\bin\repro\x64\Debug\compile-with-Release-libs.rsp`.
 * Build & run ILCompiler using **F5**. This will compile the repro project into an `.obj` file. You can debug the compiler and set breakpoints in it at this point.
 * The last step is linking the object file into an executable so that we can launch the result of the AOT compilation.
 * Open the src\coreclr\tools\aot\ILCompiler\reproNative\reproNative.vcxproj project in Visual Studio. This project is configured to pick up the `.obj` file we just compiled and link it with the rest of the runtime.