README: pin neutral serving branch serving/arvq-v4-v5 (same commit d7ada6d)

README.md

@@ -52,11 +52,13 @@ regression; treat general-English quality accordingly.
 ## Serving (vLLM)
 
 Serve with the SM120 fork `github.com/jarrelscy/vllm-glm52-sm120`, branch
-`experiment/arvq-mcbook16`, commit `d7ada6d` or later. That build loads the
-v4 cold-expert format `rvq256_256x8_expert_fp16block` used by all PV-replaced
-layers here (fitted FP16 block scales serialized directly, applied in FP32
-after the FP4 MMA; experimental ABI — rebuild the ARVQ libraries together
-with the loader via arvq/build.sh). The config.json `arvq` marker declares
+`serving/arvq-v4-v5`, commit `d7ada6d` or later (the same commit is the tip
+of `experiment/arvq-mcbook16`; one serving line loads v3, v4 and v5
+checkpoints). That build loads the v4 cold-expert format
+`rvq256_256x8_expert_fp16block` used by all PV-replaced layers here (fitted
+FP16 block scales serialized directly, applied in FP32 after the FP4 MMA;
+experimental ABI — rebuild the ARVQ libraries together with the loader via
+arvq/build.sh). The config.json `arvq` marker declares
 format version 4 to match. Earlier branches cannot load this repo:
 `experiment/arvq-fp16-block-scales` (00f57ca51) registers uint8 E4M3 scales
 and predates the v4 format string; the `glm52-sm120` main branch and the v3