Tuple types with spreads

Reader comment https://www.gitbook.com/book/basarat/typescript/discussions/72 :rose: Quote:

> If you want a tuple type like `[string, boolean, ...number]`, you can use `interface YourName extends Array { 0: string, 1: number }`

Start with the quoted reader discussion and locate the book's existing coverage of tuple types. Clarify whether the requested work is to document tuple types with spreads, then update the relevant section so the syntax and example are accurate.

Written by the indexing model from the issue text.