docs(orderBy): describe your change...

Documentation updates to clarify default sort behavior. See
#15293 for more information

Author: arw-travela

src/ng/filter/orderBy.js

@@ -8,7 +8,8 @@
  * @description
  * Orders a specified `array` by the `expression` predicate. It is ordered alphabetically
  * for strings and numerically for numbers. Note: if you notice numbers are not being sorted
- * correctly, make sure they are actually being saved as numbers and not strings.
+ * correctly, make sure they are actually being saved as numbers and not strings and are not
+ * null or undefined.
  *
  * @param {Array} array The array to sort.
  * @param {function(*)|string|Array.<(function(*)|string)>=} expression A predicate to be