fix: use the correct max tokens parameter name in example (#773)

Author: achartier

docs/llmapi.md

@@ -29,15 +29,15 @@ python3 tensorrt_llm/triton_backend/scripts/launch_triton_server.py --model_repo
 * Send request
 
 ```bash
-curl -X POST localhost:8000/v2/models/tensorrt_llm/generate -d '{"text_input": "The future of AI is", "max_tokens":10}' | jq
+curl -X POST localhost:8000/v2/models/tensorrt_llm/generate -d '{"text_input": "The future of AI is", "sampling_param_max_tokens":10}' | jq
 ```
 
 * Optional: include performance metrics
 
 To retrieve detailed performance metrics per request such as KV cache usage, timing breakdowns, and speculative decoding statistics - add `"sampling_param_return_perf_metrics": true` to your request payload:
 
 ```bash
-curl -X POST localhost:8000/v2/models/tensorrt_llm/generate -d '{"text_input": "Please explain to me what is machine learning?", "max_tokens":10, "sampling_param_return_perf_metrics":true}' | jq
+curl -X POST localhost:8000/v2/models/tensorrt_llm/generate -d '{"text_input": "Please explain to me what is machine learning?", "sampling_param_max_tokens":10, "sampling_param_return_perf_metrics":true}' | jq
 ```
 
 Sample response with performance metrics