Add cookbook variants for Try Valkey (caching, rate limiting, leaderboards, queues)

[cnuthalapati]

Context

We'd like to contribute a set of focused tutorial pages for the Try Valkey emulator. Our team has several PMs who want to submit PRs for these. This builds on #526 (tutorial panel mechanism).

Problem

The current Try Valkey page is general-purpose but doesn't help users learn specific patterns. Developers typically come to Valkey for a concrete use case (caching, rate limiting, leaderboards, queues) and want to see those patterns in action immediately.

Proposal

Create separate cookbook pages under /try-valkey/ that each focus on one use case, using the same emulator but with a tailored tutorial panel:

• Caching patterns - cache-aside with SET EX, conditional SET NX, TTL management, key naming conventions
• Rate limiting - INCR + EXPIRE fixed window, sorted set sliding window, token bucket with Lua
• Leaderboards - ZADD, ZRANK, ZINCRBY, ZREVRANGE top-N, time-bucketed scores
• Queues - LPUSH/BRPOP simple queue, XADD/XREAD/XGROUP consumer group streams

Each cookbook is a new markdown file (e.g., content/try-valkey/caching.md) that references the same VM state but provides its own set of example commands for the tutorial panel.

Implementation per cookbook

• One new markdown file in content/try-valkey/
• Front matter defines the cookbook-specific commands and descriptions
• Same emulator, same template, different panel content
• Each page is self-contained: intro paragraph + clickable commands + one-line explanations

Why this matters

• Users learn by doing, in context, with zero setup
• Each cookbook takes 20-30 minutes to write (just example commands and one-line descriptions)
• High discoverability: /try-valkey/caching/ is a shareable URL for specific use cases
• Multiple contributors can work on different cookbooks in parallel

Would you be open to accepting PRs for these?

[stockholmux]

In general, I'm aligned with the idea.

I think some of this would probably need to reside in valkey-doc.