Add versioning policy to documentation #19950

Job	Run time
cargo test \| ubuntu-latest	7m 1s
cargo clippy	2m 25s
cargo test \| windows-latest	9m 11s
Determine changes	13s
cargo fmt	17s
cargo fuzz	6m 5s
cargo test (wasm)	1m 54s
cargo udeps	2m 46s
test scripts	1m 10s
benchmarks	13m 29s
mkdocs	2m 46s
pre-commit	2m 3s
python package	1m 56s
Formatter ecosystem and progress checks	4m 5s
ecosystem	7m 8s
	1h 2m 29s

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