Is it worth mentioning the limitations of fixed-size vectors (i.e. the fact they don't implement traits), just as a `> Note: fixed-size vectors have bugs....`?

(Also, this "because ..." doesn't seem necessary (i.e. just say "Fixed-size strings do not exist."), since e.g. string literals are immutable, so they could, in theory, be `[u8, .. len]` behind the scenes.)