remove unneccessary admonition from choose docs

IteratorRandom::choose also guarantees O(1) performance for slices, so
there is no need to recommend an alternative

src/seq/mod.rs

@@ -296,9 +296,6 @@ pub trait IteratorRandom: Iterator + Sized {
     /// depends on size hints. In particular, `Iterator` combinators that don't
     /// change the values yielded but change the size hints may result in
     /// `choose` returning different elements.
-    ///
-    /// For slices, prefer [`SliceRandom::choose`] which guarantees `O(1)`
-    /// performance.
     fn choose<R>(mut self, rng: &mut R) -> Option<Self::Item>
     where R: Rng + ?Sized {
         let (mut lower, mut upper) = self.size_hint();