[Core] Clarify the deprecation notice for isEmptyOrWhitespace.

src/Three20Core/Headers/NSStringAdditions.h

@@ -30,7 +30,24 @@
 
 /**
  * Determines if the string is empty or contains only whitespace.
- * @deprecated Use TTIsStringWithAnyText: instead.
+ * @deprecated Use TTIsStringWithAnyText() instead. Updating your use of
+ * this method is non-trivial. See the note below.
+ *
+ * Notes for updating your use of isEmptyOrWhitespace:
+ *
+ * if (!textField.text.isEmptyOrWhitespace) {
+ *
+ * becomes
+ *
+ * if (TTIsStringWithAnyText(textField.text) && !textField.text.isWhitespaceAndNewlines) {
+ *
+ * and
+ *
+ * if (textField.text.isEmptyOrWhitespace) {
+ *
+ * becomes
+ *
+ * if (0 == textField.text.length || textField.text.isWhitespaceAndNewlines) {
  */
 - (BOOL)isEmptyOrWhitespace __TTDEPRECATED_METHOD;