docs: restructure documentation with quickstart, concepts, and new nav #517

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	33s
checks / test (3.10, lowest-direct, windows-latest)	3m 3s
checks / test (3.10, lowest-direct, ubuntu-latest)	51s
checks / test (3.11, lowest-direct, windows-latest)	2m 34s
checks / test (3.11, lowest-direct, ubuntu-latest)	54s
checks / test (3.11, locked, ubuntu-latest)	48s
checks / test (3.12, locked, ubuntu-latest)	52s
checks / test (3.11, locked, windows-latest)	2m 28s
checks / test (3.10, locked, windows-latest)	2m 34s
checks / test (3.12, locked, windows-latest)	3m 30s
checks / test (3.10, locked, ubuntu-latest)	48s
checks / test (3.12, lowest-direct, ubuntu-latest)	55s
checks / test (3.14, lowest-direct, windows-latest)	2m 18s
checks / test (3.12, lowest-direct, windows-latest)	3m 51s
checks / test (3.13, lowest-direct, windows-latest)	2m 42s
checks / test (3.14, locked, ubuntu-latest)	2m 19s
checks / test (3.13, locked, ubuntu-latest)	49s
checks / test (3.14, locked, windows-latest)	3m 11s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 15s
checks / test (3.13, lowest-direct, ubuntu-latest)	54s
checks / test (3.13, locked, windows-latest)	2m 22s
all-green	2s
	39m 44s

Provide feedback