3bc6c28376
Update the examples in `String` and `VecDeque::retain` The examples added in #60396 used a "clever" post-increment hack, unrelated to the actual point of the examples. That hack was found [confusing] in the users forum, and #81811 already changed the `Vec` example to use a more direct iterator. This commit changes `String` and `VecDeque` in the same way for consistency. [confusing]: https://users.rust-lang.org/t/help-understand-strange-expression/62858