The notation used here (e.g. "transmute `t: T` to `Option<T>`") felt
maybe a bit heavy, in the context of the library documentation, so
let's elaborate this a bit.
Also, in the `Option` docs, we talk about this being true for "the
following types `T`", but it felt this caveat might get a bit lost in
the next sentence that talks about the valid transmutations, so let's
reiterate the caveat.
While we're touching the line, we can improve:
> The only difference is the implied semantics:
This sentence was a bit awkward due to the mismatched plurality and
not identifying the difference being spoken to. We'll reword this to
make it more clear.
We'll wrap to 80, since the existing text and most of the doc comments
in these files are wrapped this way.
73f5fe78d4