### What it does
Checks for `ref` bindings which create a reference to a reference.

### Why is this bad?
The address-of operator at the use site is clearer about the need for a reference.

### Example
```
let x = Some("");
if let Some(ref x) = x {
    // use `x` here
}
```

Use instead:
```
let x = Some("");
if let Some(x) = x {
    // use `&x` here
}
```