fix typo in pipeline user guide
@@ -14,7 +14,7 @@ Pipeline: chaining estimators
:class:`Pipeline` can be used to chain multiple estimators
into one. This is useful as there is often a fixed sequence
of steps in processing the data, for example feature selection, normalization
-and classification. :class:`Pipeline` serves two purposes here:
+and classification. :class:`Pipeline` serves multiple purposes here:
Convenience and encapsulation
You only have to call ``fit`` and ``predict`` once on your
