Rollup merge of rust-lang#131858 - AnthonyMikh:AnthonyMikh/repeat_n-i…

…s-not-that-special-anymore, r=jhpratt

Remove outdated documentation for `repeat_n`

After rust-lang#106943, which made `Take<Repeat<I>>` implement `ExactSizeIterator`, part of documentation about difference from `repeat(x).take(n)` is no longer valid.

```@rustbot``` labels: +A-docs, +A-iterators

library/core/src/iter/sources/repeat_n.rs

@@ -8,9 +8,7 @@ use crate::num::NonZero;
 /// The `repeat_n()` function repeats a single value exactly `n` times.
 ///
 /// This is very similar to using [`repeat()`] with [`Iterator::take()`],
-/// but there are two differences:
-/// - `repeat_n()` can return the original value, rather than always cloning.
-/// - `repeat_n()` produces an [`ExactSizeIterator`].
+/// but `repeat_n()` can return the original value, rather than always cloning.
 ///
 /// [`repeat()`]: crate::iter::repeat
 ///