Add benchmarkmpsgraph-command branch to experimental branches table

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ChinChangYang

docs/CoreML_FP16_Investigation.md

@@ -253,6 +253,7 @@ for i in 0..<ownershipCount { ownership[i] = Float32(ownershipFP16[i]) }
 | `vimage-conversion` | vImage conversion experiment |
 | `coreml-backend` | Base CoreML backend implementation |
 | `fp16-gpu-only-isolation` | FP16 conversion isolated to GPU-only mode (Phase 6, 7, 9, 10) |
+| `benchmarkmpsgraph-command` | New benchmarkmpsgraph command, GPU_FP16_ONLY bug fix, per-block profiling infrastructure (Phase 12, 13) |
 
 ## Phase 8: Output Conversion Profiling (Fact-Check)