Fix documentation for Iterator::count().

src/libcore/iter/traits/iterator.rs

@@ -201,13 +201,13 @@ pub trait Iterator {
 
     /// Consumes the iterator, counting the number of iterations and returning it.
     ///
-    /// This method will evaluate the iterator until its [`next`] returns
-    /// [`None`]. Once [`None`] is encountered, `count()` returns one less than the
-    /// number of times it called [`next`]. Note that [`next`] has to be called at
-    /// least once even if the iterator does not have any elements.
+    /// This method will call [`next`] repeatedly until [`None`] is encountered,
+    /// returning the number of times it saw [`Some`]. Note that [`next`] has to be
+    /// called at least once even if the iterator does not have any elements.
     ///
     /// [`next`]: #tymethod.next
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Some`]: ../../std/option/enum.Option.html#variant.Some
     ///
     /// # Overflow Behavior
     ///