docs: first draft of an AI policy in CONTRIBUTING.md (#694) #9

Job	Run time
Build (x86_64/linux)	4m 55s
Test (macOS)	3m 43s
Test (linux/aarch64)	3m 4s
Build (aarch64/macos)	6m 0s
Source code checks (stable, macos-latest)	2m 5s
Source code checks (1.87.0, windows-2025)	3m 21s
Check for unneeded dependencies	1m 24s
Build (x86_64/linux-musl)	3m 2s
Build (x86_64/windows)	3m 18s
Source code checks (stable, windows-2025)	6m 2s
Test (linux/x86_64)	3m 14s
Source code checks (1.87.0, ubuntu-24.04)	1m 18s
Source code checks (stable, ubuntu-24.04)	2m 8s
Source code checks (1.87.0, macos-latest)	1m 59s
Build (wasm32/unknown)	1m 50s
Build (aarch64/linux)	3m 49s
Benchmarks	0s
Build (wasm32/wasi-0.2)	2m 6s
Analyze public API	0s
OS target tests (Fedora/latest)	32s
External tests / bash-completion test suite	9m 7s
OS target tests (Debian/testing)	25s
OS target tests (NixOS/latest)	1m 11s
OS target tests (Azure Linux/3.0)	38s
OS target tests (Arch Linux/latest)	30s
OS target tests (openSUSE Tumbleweed/latest)	37s
	1h 6m 18s

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