docs: fix stub pages and improve docs structure #4199

Job	Run time
checks / test (3.13, lowest-direct, windows-latest)	2m 28s
checks / readme-snippets	10s
checks / test (3.11, highest, ubuntu-latest)	46s
checks / pre-commit	31s
checks / test (3.12, highest, ubuntu-latest)	50s
checks / test (3.13, highest, windows-latest)	2m 29s
checks / test (3.11, lowest-direct, windows-latest)	2m 22s
checks / test (3.13, lowest-direct, ubuntu-latest)	44s
checks / test (3.13, highest, ubuntu-latest)	45s
checks / test (3.10, highest, windows-latest)	2m 18s
checks / test (3.10, highest, ubuntu-latest)	48s
checks / test (3.10, lowest-direct, ubuntu-latest)	46s
checks / test (3.11, lowest-direct, ubuntu-latest)	46s
checks / test (3.12, highest, windows-latest)	3m 27s
checks / test (3.11, highest, windows-latest)	2m 47s
checks / test (3.12, lowest-direct, ubuntu-latest)	48s
checks / test (3.10, lowest-direct, windows-latest)	2m 19s
checks / test (3.12, lowest-direct, windows-latest)	3m 6s
all-green	5s
	28m 15s

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