🧹 [Maintenance]: Update Benchmark documentation

[gaby]

Maintenance Task Description

The current documentation for benchmark in v3 points to Fiber v1. The page is also pointing to an older version of the TechEmpower cores.

https://docs.gofiber.io/next/extra/benchmarks/

Impact on the Project

High, since the benchmarks do not match the current version.

Additional Context (optional)

N/a

Checklist:

• I have confirmed that this maintenance task is currently not being addressed.
• I understand that this task will be evaluated by the maintainers and prioritized accordingly.
• I am available to provide further information if needed.