Update liballoc vec doc link

Author: pickfire

library/alloc/src/vec.rs

@@ -2620,7 +2620,6 @@ where
 ///
 /// This `struct` is created by the `into_iter` method on [`Vec`] (provided
 /// by the [`IntoIterator`] trait).
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct IntoIter<T> {
     buf: NonNull<T>,
@@ -2800,9 +2799,7 @@ unsafe impl<#[may_dangle] T> Drop for IntoIter<T> {
 
 /// A draining iterator for `Vec<T>`.
 ///
-/// This `struct` is created by the [`drain`] method on [`Vec`].
-///
-/// [`drain`]: struct.Vec.html#method.drain
+/// This `struct` is created by [`Vec::drain`].
 #[stable(feature = "drain", since = "1.6.0")]
 pub struct Drain<'a, T: 'a> {
     /// Index of tail to preserve
@@ -2930,10 +2927,8 @@ impl<T> FusedIterator for Drain<'_, T> {}
 
 /// A splicing iterator for `Vec`.
 ///
-/// This struct is created by the [`splice()`] method on [`Vec`]. See its
-/// documentation for more.
-///
-/// [`splice()`]: struct.Vec.html#method.splice
+/// This struct is created by [`Vec::splice()`].
+/// See its documentation for more.
 #[derive(Debug)]
 #[stable(feature = "vec_splice", since = "1.21.0")]
 pub struct Splice<'a, I: Iterator + 'a> {