[duckdb/#12978] - Use Slurm env vars to manage cpu and memory allocation if run inside Slurm HPC job needs documentation

[duckdblabs-bot]

See https://github.com/duckdb/duckdb/issues/12978

[Tishj]

Documenting the CGroup compatibility for available memory and thread count could be nice, seeing as more interest is starting to develop around vertically scaling DuckDB on cloud providers