[objects] update discussion on reserved word usage. fixes #61

Author: hshoff

README.md

@@ -83,23 +83,40 @@
     var item = {};
     ```
 
-  - Don't use [reserved words](https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Reserved_Words) as keys.
+  - Don't use [reserved words](http://es5.github.io/#x7.6.1) as keys. It won't work in IE8. [More info](https://github.com/airbnb/javascript/issues/61)
 
     ```javascript
     // bad
     var superman = {
-      class: 'superhero',
       default: { clark: 'kent' },
       private: true
     };
 
     // good
     var superman = {
-      klass: 'superhero',
       defaults: { clark: 'kent' },
       hidden: true
     };
     ```
+
+  - Use readable synonyms in place of reserved words.
+
+    ```javascript
+    // bad
+    var superman = {
+      class: 'alien'
+    };
+
+    // bad
+    var superman = {
+      klass: 'alien'
+    };
+
+    // good
+    var superman = {
+      type: 'alien'
+    };
+    ```
     **[[⬆]](#TOC)**
 
 ## <a name='arrays'>Arrays</a>