Fills missing documentation and adds warn(missing_docs) (#1525) #510

Job	Run time
clippy/stable	20s
Pass MSRV values to other jobs	4s
nostd/thumbv6m-none-eabi/stable	23s
docs/nightly	24s
format/nightly	13s
miri	11m 2s
cargo-careful	2m 16s
cross_test/i686-unknown-linux-gnu/stable	1m 58s
cross_test/s390x-unknown-linux-gnu/stable	8m 12s
blas-msrv	1m 0s
tests/1.64.0	3m 26s
tests/beta	2m 18s
tests/nightly	3m 4s
tests/stable	2m 8s
conclusion	4s
	36m 52s

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