Document @. exceptions for ' and : (#53746)
This documents that postfix `'` and infix `:` don't have a dotted
version and that they're not affected by `@.`.
I hesitated to mention also that syntax sugar like `[1:2, 3:4]` for
`Base.vect(1:2, 3:4)` is also unaffected by `@.`, but I think that may
be more confusing than helpful and anyway people are unlikely to expect
that `@. [1:2, 3:4]` will broadcast.
Fixes #53622
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Co-authored-by: Andy Dienes <51664769+adienes@users.noreply.github.com>
