docs: add README for building bench_simple on Windows (MSVC)

Author: ProgrammerKR

tools/bench/README_MSVS.md

@@ -0,0 +1,17 @@
+# Building `bench_simple` on Windows (MSVC)
+
+Prerequisites
+- Visual Studio (Build Tools) with C/C++ workload installed.
+
+Steps
+1. Open "Developer Command Prompt for VS" (or run `VsDevCmd.bat` for your VS installation).
+2. From that prompt, run the PowerShell build script included here:
+
+```powershell
+cd tools/bench
+pwsh .\build_msvc.ps1
+```
+
+Notes
+- The build script expects `cl.exe` on PATH. If you get an error, ensure you launched the Developer Command Prompt.
+- The script compiles `bench_simple.c` together with `src\vm\vm_dispatch.c` and `src\vm\bytecode.c` and produces `bench_simple.exe` in the same folder.