fix according to comment

python/paddle/reader/__init__.py

@@ -12,4 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# It would be too lengthy to require our users to prefix decorators with `decorator`.
+# For example, we want the following line
+#
+#     r = paddle.reader.decorator.bufferd(paddle.reader.creator.text("hello.txt"))
+#
+# to be a shorter version:
+#
+#     r = paddle.reader.buffered(paddle.reader.creator.text("hello.txt"))
 from decorator import *