### What it does
Checks for `into_iter` calls on references which should be replaced by `iter`
or `iter_mut`.

### Why is this bad?
Readability. Calling `into_iter` on a reference will not move out its
content into the resulting iterator, which is confusing. It is better just call `iter` or
`iter_mut` directly.

### Example
```
(&vec).into_iter();
```

Use instead:
```
(&vec).iter();
```