Note that the -> pair factory method, defined for arbitrary types in Scala’s Predef, is unrelated to this type alias.
The -> type probably is intended for infix notation, i.e. instead of ->[Int, String] you’d write Int -> String. (Infix notation works for any type with two parameters, although it only shines with operator-like type names - you can write Int Either String, as well.)
Your link to the FAQ has a section, “Methods provided by implicit conversion”, which talks about ->.
Unfortunately, the link to an index in the Scaladoc is broken. It used to point here, where the entry for -> points to ArrowAssoc. The Scaladoc for that isn’t useful, but at least you know where the operator is introduced, so you could grep for it in the open source project.
I don’t know why it’s called open source instead of greppable source.