add softsign into doc.

lcy-seso · lcy-seso · commit 93a225563939 · 2017-12-07T17:52:13.000+08:00
diff --git a/doc/api/v2/config/activation.rst b/doc/api/v2/config/activation.rst
@@ -99,3 +99,10 @@ STanh
 ..  automodule:: paddle.v2.activation
     :members: STanh
     :noindex:
+    
+SoftSign
+========
+
+..  automodule:: paddle.v2.activation
+    :members: SoftSign
+    :noindex:
