Based on a discussion on #rust-beginners the existing note for drain is confusing. This new wording was suggested.
/// Create a draining iterator that removes the specified range in the vector
/// and yields the removed items.
///
- /// Note 1: The element range is removed even if the iterator is not
- /// consumed until the end.
+ /// Note 1: The element range is removed even if the iterator is only
+ /// partially consumed or not consumed at all.
///
/// Note 2: It is unspecified how many elements are removed from the vector,
/// if the `Drain` value is leaked.