Rust Guidelines: Paging page types should reference the current model/iterator guidance

Bad code snippet:
```rust
pub struct FeedPage {}
```

What it should do:
The current Rust guidance is out of date. The feedback in APIView correctly points to the cited paging/model guidelines, but those guidelines no longer reflect the intended shape for Rust paging types in `azure_data_cosmos`. Please update the official Rust guideline so it clearly describes the current requirements for page types (including `azure_core::Model` and `IntoIterator` behavior, if still applicable).

Good code snippet:
```rust
pub struct FeedPage {
// page fields
}

impl azure_core::Model for FeedPage {
// current expected implementation
}

impl IntoIterator for FeedPage {
type Item = T;
type IntoIter = std::vec::IntoIter;

fn into_iter(self) -> Self::IntoIter {
// iterate over page items
}
}
```

Locate the cited Rust paging and model guidelines, then compare them with the current azure_data_cosmos page types. Confirm whether azure_core::Model and IntoIterator remain required, and update the official guidance so its requirements and examples match the current intended shape.

Written by the indexing model from the issue text.