Documentation: add recommended VSCode configuration files

[rileyjmurray]

@TeachRaccooon and I use VSCode for RandLAPACK development. We should make note of recommended VSCode configurations for people who want to try out RandLAPACK, run its benchmarks, etc..

Here's the configuration file I use for my main RandNLA development folder on my macOS machine.

{
    "configurations": [
        {
            "cppStandard": "c++20",
            "cStandard": "c17",
            "macFrameworkPath": [
                "/System/Library/Frameworks",
                "/Library/Frameworks"
            ],
            "intelliSenseMode": "macos-clang-arm64",
            "compilerPath": "/opt/homebrew/opt/llvm/bin/clang",
            "includePath": [
                "${default}",
                "${workspaceFolder}/RandBLAS",
                "${workspaceFolder}/RandLAPACK",
                "${workspaceFolder}/blaspp-install/include",
                "${workspaceFolder}/lapackpp-install/include",
                "${workspaceFolder}/Random123-install/include",
                "/opt/homebrew/opt/googletest/include"
            ]
        }
    ],
    "version": 4
}