#2538 docs: link strata-bench from the community benchmarks guide

Descripción

This adds one paragraph to docs/COMMUNITY_BENCHMARKS.md, under "Run the benchmark", linking strata-bench, the common benchmark format and comparison page proposed in #713.

On 7 October, in #713, you [wrote](https://github.com/Niko1221/Strata/issues/713#issuecomment-6037757374): "We will link it from docs/COMMUNITY_BENCHMARKS.md once it exists." The repository exists now, so I am sending the link as a pull request.

What it changes: one paragraph in docs/COMMUNITY_BENCHMARKS.md.
What it leaves alone: tools/strata_bench.py, the report template and format, and the list of community reports.

Screenshot of the [live dashboard](https://brenoperucchi.github.io/strata-bench/). The code is in the [repository](https://github.com/brenoperucchi/strata-bench).

[![strata-bench dashboard](https://raw.githubusercontent.com/brenoperucchi/strata-bench/d2722106e73a06b25c9455309300b2df38384fb0/docs/img/dashboard.png)](https://brenoperucchi.github.io/strata-bench/)

strata-bench is independent of Strata, MIT licensed and maintained by me. If you would rather not link it, or want other wording, tell me and I will change or close this pull request.