Switch `<>` back to `[]`

Here we go.

Thoughts?
s/form/from/

I’d also reword this; perhaps something like “4. At the time when Rust switched from `[]` to `<>` there was no precedence in a C-style language for `[]` generics; this no longer true: Scala is an example of a language that has become fairly popular recently and which uses `[]` for its generics syntax.”