Merge pull request #2464 from luotao1/rnn_doc

update rnn doc from v1-api to v2-api.

doc/howto/deep_model/rnn/index_cn.rst

@@ -4,6 +4,7 @@ RNN相关模型
 ..  toctree::
   :maxdepth: 1
 
+  rnn_config_cn.rst
   recurrent_group_cn.md
   hierarchical_layer_cn.rst
   hrnn_rnn_api_compare_cn.rst

doc/howto/deep_model/rnn/index_en.rst

@@ -1,2 +1,7 @@
 RNN Models
 ==========
+
+..  toctree::
+  :maxdepth: 1
+
+  rnn_config_en.rst