Document the benchmark configuration CSV

[sylvesterkaczmarek]

Summary

• document that benchmark processing requires a manually created currentConfig.csv
• provide the exact 11-field header and a valid two-line example
• explain the boolean fields and the platform, core, compiler, and version values
• correct the claim that CMake generates the file automatically

Context

Both processResult.py and summaryBench.py locate currentConfig.csv beside the result file supplied with -r. The generator was removed because it was not generic enough, but the README still says that CMake creates the file and does not describe its format.

Fixes #253.

Validation

• git diff --check
• parsed the documented example with Python's CSV reader and verified that it contains one header row, one data row, and 11 matching fields
• verified the file lookup in both processResult.py and summaryBench.py

Documentation-only change. No code tests were run.

[sylvesterkaczmarek]

Refreshed this PR onto current main today. It is mergeable, with no failing/error checks or outstanding changes-requested reviews. This has been quiet since August. Could a maintainer please review it when convenient, or let me know if anything further is needed?