docs: pin FlashInfer/ModelOpt versions in upstream-mapping

docs/design/skip_softmax_sage_trtllm_gen.md

@@ -61,6 +61,8 @@ Env var = flag in UPPER_SNAKE (e.g. `TRTLLM_GEN_SAGE=1`).
 | `target_sparsity` | `threshold_scale_factor` (via calibration) | `skip_softmax_threshold_scale_factor` |
 | `disabled_until_timestep` | — (DiT-only) | host gate |
 
+Versions: **FlashInfer 0.6.5 · ModelOpt 0.44.0** (runtime deps); TRT-LLM = naming reference (blog16, no runtime dep).
+
 ---
 
 ## Part 2 — Testing Plan