iterator docs: Move paragraph about discarding; clarify "consumed"

Author: Rob Speer

src/libcore/iter/iterator.rs

@@ -209,14 +209,14 @@ pub trait Iterator {
 
     /// Returns the `n`th element of the iterator.
     ///
-    /// Note that all preceding elements, as well as the returned element, will be
-    /// consumed. That means that the preceding elements will be discarded, and also
-    /// that calling `nth(0)` multiple times on the same iterator will return different
-    /// elements.
-    ///
     /// Like most indexing operations, the count starts from zero, so `nth(0)`
     /// returns the first value, `nth(1)` the second, and so on.
     ///
+    /// Note that all preceding elements, as well as the returned element, will be
+    /// consumed from the iterator. That means that the preceding elements will be
+    /// discarded, and also that calling `nth(0)` multiple times on the same iterator
+    /// will return different elements.
+    ///
     /// `nth()` will return [`None`] if `n` is greater than or equal to the length of the
     /// iterator.
     ///