docs(nodes): reference OpenChainBench for live public RPC latency

[Flotapponnier]

Summary

Adds a one-line reference to OpenChainBench — Celo RPC at the end of the Community RPC Node discovery list in tooling/nodes/overview.mdx, so developers picking a public endpoint can see live third-party latency comparisons.

Why

The existing discovery list already includes third-party tools (Vido, Celo Community RPC Gateway, Stakely). OpenChainBench probes public no-key Celo endpoints from three regions every minute and publishes p50/p95/p99 latency, providing the same discovery utility with a live latency dimension.

• Open methodology: https://openchainbench.com/methodology
• Data license: CC-BY-4.0
• No affiliation with cLabs / Celo

Happy to reword or move if this doesn't fit the docs' tone.

Test plan

• Single-line addition inside an existing bullet list
• Matches surrounding link style

[Flotapponnier]

Just bumping this in case it got buried under other PRs. Happy to adjust the wording or placement if that would help!

[GigaHierz]

Thanks for the contribution, and for being upfront about the methodology, licensing, and lack of affiliation — that’s appreciated.

We’re going to pass on this one, though. The “Use a Community RPC Node” list is specifically for ways to discover and connect to actual endpoints (the CLI command, Vido, the Community RPC Gateway, Stakely). OpenChainBench is a third-party benchmarking site rather than an endpoint source, and the endpoints it measures are the hosted “as-a-service” providers, not the Community RPC nodes this section is about — so it doesn’t fit here.

More broadly, we’d rather not link out to external dashboards we don’t control in the node docs, since their uptime, methodology, and accuracy can change without notice and readers tend to read anything in our docs as a recommendation.

Appreciate the effort — closing this one out.