RFC, chore: shrink `series` module docstrings #6473

Job	Run time
pytest-38 (3.8, windows-latest)	1m 25s
pytest-full-coverage (3.11, ubuntu-latest)	4m 46s
pytest-38 (3.8, ubuntu-latest)	47s
pytest-full-coverage (3.13, ubuntu-latest)	2m 51s
pytest-windows (3.10, windows-latest)	11m 44s
pytest-windows (3.12, windows-latest)	3m 39s
	25m 12s

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