Org-expiry: make code and doc consistent

* contrib/lisp/org-expiry.el (org-expiry-expired-p): make code and doc
string consistent.

contrib/lisp/org-expiry.el

@@ -218,11 +218,12 @@ Return nil if the entry is not expired.  Otherwise return the
 amount of time between today and the expiry date.
 
 If there is no creation date, use `org-expiry-created-date'.
-If there is no expiry date, use `org-expiry-expiry-date'."
+If there is no expiry date, use `org-expiry-wait'."
   (let* ((ex-prop org-expiry-expiry-property-name)
 	 (cr-prop org-expiry-created-property-name)
 	 (ct (current-time))
-	 (cr (org-read-date nil t (or (org-entry-get (point) cr-prop t) "+0d")))
+	 (cr (org-read-date nil t (or (org-entry-get (point) cr-prop t)
+				      org-expiry-created-date)))
 	 (ex-field (or (org-entry-get (point) ex-prop t) org-expiry-wait))
 	 (ex (if (string-match "^[ \t]?[+-]" ex-field)
 		 (time-add cr (time-subtract (org-read-date nil t ex-field) ct))