Outdated docstrings

Docstrings throughout the project don't reflect the official API documentation anymore.

When we'll be updating them, what do you think about following this template?
```Rust
/// Description
///
/// Further precisions *(Optional)*
///
///
```

For example:
```Rust
/// Remove a KV pair from the namespace.
///
/// Use URL-encoding to use special characters (for example, `:`, `!`, `%`) in the key name.
///
///
```

Start by locating the project's existing Rust docstrings and compare them with the official Cloudflare API documentation, using the KV delete example as a formatting reference. Update outdated docstrings throughout the project to follow the proposed template and verify that descriptions, optional details, and API URLs are accurate.

Written by the indexing model from the issue text.