Update documentation to demonstrate the use of output rails when using a custom RAG

[niels-garve]

Hi @drazvan,

First, thanks for NeMo Guardrails.

With this pull request, I add an example that demonstrates the use of output rails when using a custom RAG.

Please refer to the README files that come with this pull request.

Fixes #227

• Documentation The example is documented and linked from the Guardrails Library docs.
• Tests Passing
• Changelog Updated I decided not to reflect the documentation changes in the changelog
• Code Style and Quality
• Commit Guidelines
• No Merge Conflicts
• Self Review

How to test

$ export OPENAI_API_KEY='your API key'
$ nemoguardrails chat --config <your_root>/NeMo-Guardrails/examples/configs/rag/custom_rag_output_rails --verbose

You may be prompted to install: pip install langchain-openai because this example uses it.

[drazvan]

Looks good @niels-garve! Thanks a lot for this great example.