Add README for vLLM example model

[elatt]

This repository is public. Do not put here any private DataRobot or customer's data: code, datasets, model artifacts, .etc.

Summary

• Cleanup NIM example README
• Update to use latest version of Llama model
• Adds README for vLLM template

Rationale

It's useful to have fully baked examples of how to use the NIM and vLLM envs and a readme to go along with the template files is invaluable.

[engprod-2[bot]]

The Needs Review labels were added based on the following file changes.

Team @datarobot/custom-models (#custom-models) was assigned because of changes in files:

model_templates/gpu_nim_textgen/README.md
model_templates/gpu_nim_textgen/model-metadata.yaml
model_templates/gpu_vllm_textgen/README.md
model_templates/gpu_vllm_textgen/engine_config.json
model_templates/gpu_vllm_textgen/model-metadata.yaml

Team @datarobot/tracking-agent (#tracking-agent-reviews) was assigned because of changes in files:

model_templates/gpu_nim_textgen/README.md
model_templates/gpu_nim_textgen/model-metadata.yaml
model_templates/gpu_vllm_textgen/README.md
model_templates/gpu_vllm_textgen/engine_config.json
model_templates/gpu_vllm_textgen/model-metadata.yaml

If you think that there are some issues with ownership, please discuss with C&A domain at #core-backend-domain slack channel and create PR to update DRCODEOWNERS\CODEOWNERS file.

[engprod-2[bot]]

Label Needs Review: Custom Models was removed because @yakov-g is part of Custom Models domain.