Update README.md

Author: cavusmustafa

examples/openvino/llama/README.md

@@ -1,11 +1,41 @@
 
-LLAMA_CHECKPOINT=<model_directory>/consolidated.00.pth
-LLAMA_PARAMS=<model_directory>/params.json
-LLAMA_TOKENIZER=<model_directory>/tokenizer.model
+# Export Llama with OpenVINO Backend
 
-python -m extension.llm.export.export_llm \
+## Download the Model
+Follow the [instructions](../../examples/models/llama#step-2-prepare-model) to download the required model files. Export Llama with OpenVINO backend is only verified with Llama-3.2-1B variants at this time. 
+
+## Environment Setup
+Follow the [instructions](../../backends/openvino/README.md) of **Prerequisites** and **Setup** in `backends/openvino/README.md` to set up the OpenVINO backend.
+
+## Export the model:
+Navigate into `<executorch_root>/examples/openvino/llama` and execute the commands below to export the model. Update the model file paths to match the location where your model is downloaded.
+
+```
+LLAMA_CHECKPOINT=<path/to/model/folder>/consolidated.00.pth
+LLAMA_PARAMS=<path/to/model/folder>/params.json
+LLAMA_TOKENIZER=<path/to/model/folder>/tokenizer.model
+
+python -m executorch.extension.llm.export.export_llm \
   --config llama3_2_ov_4wo_config.yaml \
   +base.model_class="llama3_2" \
   +base.checkpoint="${LLAMA_CHECKPOINT:?}" \
   +base.params="${LLAMA_PARAMS:?}" \
-  +base.tokenizer_path="${LLAMA_TOKENIZER:?}" \
+  +base.tokenizer_path="${LLAMA_TOKENIZER:?}"
+```
+
+## Build OpenVINO C++ Runtime with Llama Runner:
+First, build the backend libraries by executing the script below in `<executorch_root>/backends/openvino/scripts` folder:
+```bash
+./openvino_build.sh --cpp_runtime
+```
+Then, build the llama runner by executing the script below (with `--llama_runner` argument) also in `<executorch_root>/backends/openvino/scripts` folder:
+```bash
+./openvino_build.sh --llama_runner
+```
+The executable is saved in `<executorch_root>/cmake-out/examples/models/llama/llama_main`
+
+## Execute Inference Using Llama Runner
+Update the model tokenizer file path to match the location where your model is downloaded and replace the prompt.
+```
+./cmake-out/examples/models/llama/llama_main --model_path=llama3_2.pte --tokenizer_path=<path/to/model/folder>/tokenizer.model --prompt="Your custom prompt"
+```