Update use-langcache.md

[Jenverse]

• Removed Scope from the request as we have made that update
• Made some other minor changes to the language

[CLAassistant]

All committers have signed the CLA.

[github-actions]

Staging links:
https://redis.io/docs/staging/Jenverse-patch-1-2/operate/rc/langcache/use-langcache

[Copilot]

Pull Request Overview

This PR updates the use-langcache.md guide to remove the scope object from example requests and refine language around filtering and supported response types.

• Clarify supported response types (LLM, RAG, and agent)
• Update wording for filtering responses
• Remove scope object from all request examples

Comments suppressed due to low confidence (2)

content/operate/rc/langcache/use-langcache.md:67

• Since the scope object has been removed from examples, update this sentence to only reference adding an attributes object or reintroduce the scope examples consistently.

You can also scope the responses returned from LangCache by adding an `attributes` object or `scope` object to the request. LangCache will only return responses that match the attributes you specify.

content/operate/rc/langcache/use-langcache.md:69

• Use a JSON code fence (```json) instead of shell (sh) to improve syntax highlighting for request examples.

```sh