fix doc comments for Peekable::next_if(_eq)

Fix references to a nonexistent `consume` function in the doc comments
for `Peekable::next_if` and `Peekable::next_if_eq`.

core/src/iter/adapters/peekable.rs

@@ -269,7 +269,7 @@ impl<I: Iterator> Peekable<I> {
     /// let mut iter = (0..5).peekable();
     /// // The first item of the iterator is 0; consume it.
     /// assert_eq!(iter.next_if(|&x| x == 0), Some(0));
-    /// // The next item returned is now 1, so `consume` will return `false`.
+    /// // The next item returned is now 1, so `next_if` will return `None`.
     /// assert_eq!(iter.next_if(|&x| x == 0), None);
     /// // `next_if` saves the value of the next item if it was not equal to `expected`.
     /// assert_eq!(iter.next(), Some(1));
@@ -304,7 +304,7 @@ impl<I: Iterator> Peekable<I> {
     /// let mut iter = (0..5).peekable();
     /// // The first item of the iterator is 0; consume it.
     /// assert_eq!(iter.next_if_eq(&0), Some(0));
-    /// // The next item returned is now 1, so `consume` will return `false`.
+    /// // The next item returned is now 1, so `next_if` will return `None`.
     /// assert_eq!(iter.next_if_eq(&0), None);
     /// // `next_if_eq` saves the value of the next item if it was not equal to `expected`.
     /// assert_eq!(iter.next(), Some(1));