Remove extra period (#818)

Author: Chris Cho

source/usage-examples/deleteOne.txt

@@ -24,7 +24,7 @@ see the
 
   If your application requires the deleted document after deletion,
   consider using the
-  `collection.findOneAndDelete() <{+api+}/classes/Collection.html#findOneAndDelete>`__.
+  `collection.findOneAndDelete() <{+api+}/classes/Collection.html#findOneAndDelete>`__
   method, which has a similar interface to ``deleteOne()`` but also
   returns the deleted document.