Added example of strings starting with a number and a space

Author: Lukewh

README.md

@@ -153,7 +153,7 @@ If your editor/IDE isn't listed above, a list of available plugins can be found
     };
     ```
 
-  - Don't use quotes around keys
+  - Don't use quotes around keys unless keys contain spaces (should be avoided at all costs) or start with numbers
   ```javascript
   // bad
   var superman = {
@@ -164,6 +164,11 @@ If your editor/IDE isn't listed above, a list of available plugins can be found
   var superman = {
     type: 'alien'
   };
+
+  // good
+  var superman = {
+    '6thSense': 'bruce willis was dead the whole time'
+  };
   ```
 
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