delete recordio writer (PaddlePaddle#1123)

Author: mapingshuo

doc/fluid/api/gen_doc.sh

@@ -10,7 +10,7 @@
 #  python gen_doc.py --module_name layers.${module} --module_prefix layers --output layers/${module}.rst
 #done 
 
-for module in layers data_feeder dataset clip metrics executor initializer io nets optimizer profiler regularizer transpiler recordio_writer backward average profiler unique_name dygraph
+for module in layers data_feeder dataset clip metrics executor initializer io nets optimizer profiler regularizer transpiler backward average profiler unique_name dygraph
 do
   python gen_doc.py --module_name ${module} --module_prefix ${module} --output ${module} --to_multiple_files True
   python gen_module_index.py ${module}  fluid.${module}