style: Document sugar for nsStyleAutoArray.

components/style/gecko_bindings/sugar/ns_style_auto_array.rs

@@ -2,21 +2,27 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+//! Rust helpers for Gecko's `nsStyleAutoArray`.
+
 use gecko_bindings::structs::nsStyleAutoArray;
 use std::iter::{once, Chain, Once, IntoIterator};
 use std::slice::{Iter, IterMut};
 
 impl<T> nsStyleAutoArray<T> {
+    /// Mutably iterate over the array elements.
     pub fn iter_mut(&mut self) -> Chain<Once<&mut T>, IterMut<T>> {
         once(&mut self.mFirstElement).chain(self.mOtherElements.iter_mut())
     }
+
+    /// Iterate over the array elements.
     pub fn iter(&self) -> Chain<Once<&T>, Iter<T>> {
         once(&self.mFirstElement).chain(self.mOtherElements.iter())
     }
 
-    // Note that often structs containing autoarrays will have
-    // additional member fields that contain the length, which must be kept
-    // in sync
+    /// Returns the length of the array.
+    ///
+    /// Note that often structs containing autoarrays will have additional
+    /// member fields that contain the length, which must be kept in sync.
     pub fn len(&self) -> usize {
         1 + self.mOtherElements.len()
     }