feat: open benchmark template and doc (#1465)

## What does this PR do?
- Provide a distro template to let developer easily run the open
benchmarks llama stack supports on llama and non-llama models.
- Provide doc on how to run open benchmark eval via CLI and open
benchmark contributing guide

[//]: # (If resolving an issue, uncomment and update the line below)
(Closes #1375 )

## Test Plan
open benchmark eval results on llama, gpt, gemini and clause
<img width="771" alt="Screenshot 2025-03-06 at 7 33 05 PM"
src="https://github.com/user-attachments/assets/1bd85456-b9b9-4b37-af76-4ce1d2bac00e"
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doc preview
<img width="944" alt="Screenshot 2025-03-06 at 7 33 58 PM"
src="https://github.com/user-attachments/assets/f4e5866d-b395-4c40-aa8b-080edeb5cdb6"
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<img width="955" alt="Screenshot 2025-03-06 at 7 34 04 PM"
src="https://github.com/user-attachments/assets/629defb6-d5e4-473c-aa03-308bce386fb4"
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<img width="965" alt="Screenshot 2025-03-06 at 7 35 29 PM"
src="https://github.com/user-attachments/assets/c21ff96c-9e8c-4c54-b6b8-25883125f4cf"
/>

<img width="957" alt="Screenshot 2025-03-06 at 7 35 37 PM"
src="https://github.com/user-attachments/assets/47571c90-1381-4e2c-bbed-c4f3a60578d0"
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docs/source/concepts/evaluation_concepts.md

@@ -24,6 +24,56 @@ The Evaluation APIs are associated with a set of Resources as shown in the follo
   - Associated with `Benchmark` resource.
 
 
+## Open-benchmark Eval
+
+### List of open-benchmarks Llama Stack support
+
+Llama stack pre-registers several popular open-benchmarks to easily evaluate model perfomance via CLI.
+
+The list of open-benchmarks we currently support:
+- [MMLU-COT](https://arxiv.org/abs/2009.03300) (Measuring Massive Multitask Language Understanding): Benchmark designed to comprehensively evaluate the breadth and depth of a model's academic and professional understanding
+- [GPQA-COT](https://arxiv.org/abs/2311.12022) (A Graduate-Level Google-Proof Q&A Benchmark): A challenging benchmark of 448 multiple-choice questions written by domain experts in biology, physics, and chemistry.
+- [SimpleQA](https://openai.com/index/introducing-simpleqa/): Benchmark designed to access models to answer short, fact-seeking questions.
+- [MMMU](https://arxiv.org/abs/2311.16502) (A Massive Multi-discipline Multimodal Understanding and Reasoning Benchmark for Expert AGI)]: Benchmark designed to evaluate multimodal models.
+
+
+You can follow this contributing guidance to add more open-benchmarks to Llama Stack
+
+### Run evaluation on open-benchmarks via CLI
+
+We have built-in functionality to run the supported open-benckmarks using llama-stack-client CLI
+
+#### Spin up Llama Stack server
+
+Spin up llama stack server with 'open-benchmark' template
+```
+llama stack run llama_stack/templates/open-benchmark/run.yaml
+
+```
+
+#### Run eval CLI
+There are 3 necessary inputs to run a benchmark eval
+- `list of benchmark_ids`: The list of benchmark ids to run evaluation on
+- `model-id`: The model id to evaluate on
+- `utput_dir`: Path to store the evaluate results
+```
+llama-stack-client eval run-benchmark <benchmark_id_1> <benchmark_id_2> ... \
+--model_id <model id to evaluate on> \
+--output_dir <directory to store the evaluate results> \
+```
+
+You can run
+```
+llama-stack-client eval run-benchmark help
+```
+to see the description of all the flags that eval run-benchmark has
+
+
+In the output log, you can find the file path that has your evaluation results. Open that file and you can see you aggrgate
+evaluation results over there.
+
+
+
 ## What's Next?
 
 - Check out our Colab notebook on working examples with running benchmark evaluations [here](https://colab.research.google.com/github/meta-llama/llama-stack/blob/main/docs/notebooks/Llama_Stack_Benchmark_Evals.ipynb#scrollTo=mxLCsP4MvFqP).