docs: output rails streaming

[mikemckiernan]

Description

Document the streaming output feature.

• Update to Output Rails page because I think that's where readers will find the feature.
• Update to Output Rails section, adding a "Streaming Output Configuration" heading that's reference for the fields (if you squint a little).

Related Issue(s)

Checklist

• I've read the CONTRIBUTING guidelines.
• I've updated the documentation if applicable.
• I've added tests if applicable.
• @mentions of the person or team responsible for reviewing proposed changes.

[github-actions]

Documentation preview

https://nvidia.github.io/NeMo-Guardrails/review/pr-976

[mikemckiernan]

@Pouyanpi, if you can TAL, LMK if it's OK or I poisoned it:

• On the likely-to-be-read output rails page, show a sample config with the revised field names and default values.
• On the linked to, but otherwise impossible to find, configuration page:
  • state the reqs for enabling output streaming
  • provide reference info for the fields
  • (new) If a rail blocks a chunk of tokens, the toolkit returns JSON-looking str "{"event": "ABORT"..."
  • (new) table of sample # tokens, chunk size, context size, and # rails invocations. (This is useful info!)

[Pouyanpi]

Thank you @mikemckiernan , it looks great.

And I suppose the user already know how to activate it with chat-cli

https://nvidia.github.io/NeMo-Guardrails/review/pr-976/user-guides/advanced/streaming.html#chat-cli