docs(readme): fix vLLM config example fence to jsonc

Switch the vLLM config example from a bash code fence to jsonc and
convert its inline `#` comments to `//` so the snippet is valid JSONC.

readme.md

@@ -318,15 +318,15 @@ modelgrid cluster activate NODE # Mark a node active again
 
 High-performance inference with PagedAttention and continuous batching.
 
-```bash
+```jsonc
 {
   "id": "vllm-1",
   "type": "vllm",
   "name": "vLLM Server",
-  "gpuIds": ["nvidia-0", "nvidia-1"],  # Tensor parallelism
+  "gpuIds": ["nvidia-0", "nvidia-1"], // Tensor parallelism
   "port": 8000,
   "env": {
-    "HF_TOKEN": "your-huggingface-token"  # For gated models
+    "HF_TOKEN": "your-huggingface-token" // For gated models
   }
 }
 ```