Document + ?Sized in a few more places (#1537) #535

Job	Run time
miri	11m 5s
cross_test/s390x-unknown-linux-gnu/stable	8m 18s
cargo-careful	2m 16s
clippy/stable	19s
cross_test/i686-unknown-linux-gnu/stable	2m 7s
docs/nightly	20s
format/nightly	15s
Pass MSRV values to other jobs	2s
nostd/thumbv6m-none-eabi/stable	19s
blas-msrv	1m 4s
tests/stable	2m 26s
tests/nightly	2m 38s
tests/1.64.0	3m 31s
tests/beta	2m 16s
conclusion	3s
	36m 59s

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