Add stable-sort note to _.sortBy documentation.

Former-commit-id: 17b9818baa6ff72ce5762ec8b3cc01bbac8725bb

README.md

@@ -43,6 +43,7 @@ For more information check out these screencasts over Lo-Dash:
  * [_.indexOf](http://lodash.com/docs#indexOf) and [_.lastIndexOf](http://lodash.com/docs#lastIndexOf) accept a `fromIndex` argument
  * [_.merge](http://lodash.com/docs#merge) for a *"deep"* [_.extend](http://lodash.com/docs#extend)
  * [_.partial](http://lodash.com/docs#partial) for partial application without `this` binding
+ * [_.sortBy](http://lodash.com/docs#sortBy) performs a [stable](http://en.wikipedia.org/wiki/Sorting_algorithm#Stability) sort
  * [_.template](http://lodash.com/docs#template) utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging
  * [_.where](http://lodash.com/docs#where) for filtering collections by contained properties
  * [_.zipObject](http://lodash.com/docs#zipObject) for composing objects

doc/README.md

@@ -2185,7 +2185,7 @@ _.some([null, 0, 'yes', false]);
 ### <a id="_sortbycollection-callback--thisarg"></a>`_.sortBy(collection, callback [, thisArg])`
 <a href="#_sortbycollection-callback--thisarg">#</a> [&#x24C8;](https://github.com/bestiejs/lodash/blob/master/lodash.js#L2280 "View in source") [&#x24C9;][1]
 
-Creates a new sorted array, sorted in ascending order by the results of running each element of `collection` through a `callback`. The `callback` is bound to `thisArg` and invoked with `3` arguments; *(value, index|key, collection)*. The `callback` argument may also be the name of a property to sort by *(e.g. 'length')*.
+Creates a new array, stable sorted in ascending order by the results of running each element of `collection` through a `callback`. The `callback` is bound to `thisArg` and invoked with `3` arguments; *(value, index|key, collection)*. The `callback` argument may also be the name of a property to sort by *(e.g. 'length')*.
 
 #### Arguments
 1. `collection` *(Array|Object|String)*: The collection to iterate over.

lodash.js

@@ -678,8 +678,8 @@
   }
 
   /**
-   * Used by `sortBy` to compare transformed `collection` values, sorting them
-   * stabily in ascending order.
+   * Used by `sortBy` to compare transformed `collection` values, stable sorting
+   * them in ascending order.
    *
    * @private
    * @param {Object} a The object to compare to `b`.
@@ -2253,9 +2253,9 @@
   });
 
   /**
-   * Creates a new sorted array, sorted in ascending order by the results of
-   * running each element of `collection` through a `callback`. The `callback` is
-   * bound to `thisArg` and invoked with 3 arguments; (value, index|key, collection).
+   * Creates a new array, stable sorted in ascending order by the results of
+   * running each element of `collection` through a `callback`. The `callback`
+   * is bound to `thisArg` and invoked with 3 arguments; (value, index|key, collection).
    * The `callback` argument may also be the name of a property to sort by (e.g. 'length').
    *
    * @static