Rollup merge of #64175 - GuillaumeGomez:replace-span-when-it-should-be-div, r=Mark...

Fix invalid span generation when it should be div

Fixes #64146.

It changes basically nothing in the display... Can be checked with:

```rust
pub enum X {
    /// Some doc?
    ///
    /// with lines!
    Foo {
        /// a
        ///
        /// b
        x: u32,
        /// Doc!
        ///
        /// ```
        /// yolo
        /// ```
        y: String,
    },
    /// Doc!
    ///
    /// ```
    /// yolo
    /// ```
    Bar(String),
}
```

r? @Mark-Simulacrum