Reclassify doc/fluid menu

[shanyi15]

refer to comment in #8976
the fluid documentation has been reclassified, according to fluid docs we already have
please put them in the right location, thanks!

新手入门 doc/fluid/getstarted

基本使用概念 doc/fluid/getstarted/concepts

【保存模型】doc/fluid/getstarted/concepts/save_model
https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/getstarted/concepts/save_model/model_format.md
Design Doc: Model Format

设计思想 doc/fluid/design

设计动机和目标 doc/fluid/design/motivation

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/motivation/api.md
  PaddlePaddle Design Doc
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/motivation/refactorization.md
  Design Doc: Refactorization Overview
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/motivation/fluid.md
  Design Doc: PaddlePaddle Fluid
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/motivation/fluid_compiler.md
  PaddlePaddle Fluid: Towards a Compiled Programming Language

执行流程 doc/fluid/design/execution

1. 编译时流程
2. 运行时流程
3. 像写程序一样定义计算
   (1) https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/execution/switch.md
   Design Doc: Switch
   (2) https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/execution/if_else_op.md
   The IfElse Operator

核心概念 doc/fluid/design/concepts

1. 编译时概念 doc/fluid/design/concepts

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/README.md
  Build system
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/cpp_data_feeding.md
  C++ Data Feeding

2. 运行时概念 doc/fluid/design/concepts

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/functions_operators_layers.md
  Design Doc: Functions, Operators, and Layers
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/program.md
  Design Doc: PaddlePaddle Programs
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/design/concepts/variable.md
  变量
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/var_desc.md
  var_desc.md variable描述
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/design/concepts/tensor.md
  张量
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/tensor_array.md
  Design for TensorArray
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/design/concepts/lod_tensor.md
  LOD 张量
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/block.md
  Design Doc: Block and Scope
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/scope.md
  Design of Scope in Paddle
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/executor.md
  Executor Design Doc

数据类型 doc/fluid/design/data_type

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/data_type/float16.md
  Design Doc: float16

内存管理 doc/fluid/design/memory

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/memory/memory_optimization.md
  Memory Optimization 内存优化
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/design/memory/README.md
  基于区域的异构内存管理 是design doc

多设备支持 doc/fluid/design/muti_devices

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/muti_devices/operator_kernel_type.md
  Design Doc: The Keys of Operator Kernel Type
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/muti_devices/kernel_selection.md
  kernel_selection
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/muti_devices/kernel_hint_design.md
  kernel_hint_design

Dynamic RNN doc/fluid/design/dynamic_rnn

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/dynamic_rnn/rnn.md
  RNNOp design
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/design/dynamic_rnn/rnn_design.md

并发编程 doc/fluid/design/concurrent

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concurrent/concurrent_programming.md
  Design Doc: Concurrent Programming with Fluid
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concurrent/csp.md
  Design Doc: CSP in PaddlePaddle Fluid
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concurrent/parallel_do.md
  Design Doc: Parallel_Do in PaddlePaddle 属于多线程数据并行的设计文档

梯度更新算法 doc/fluid/design/algorithm

https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/algorithm/parameter_average.md

复杂网络设计 doc/fluid/design/network

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/network/sequence_decoder.md
  Design: Sequence Decoder Generating LoDTensors
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/network/deep_speech_2.md
  DeepSpeech2 on PaddlePaddle: Design Doc

代码结构和重要模块 doc/fluid/design/modules

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/backward.md
  Backward Building
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/evaluator.md
  Evaluator Design
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/python_api.md
  Design Doc: Python API
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/regularization.md
  Regularization in PaddlePaddle
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/infer_var_type.md
  Design Doc: InferVarType
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/optimizer.md
  Optimizer Design
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/prune.md
  Prune
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/register_grad_op.md
  Design Doc: Gradient Operators Registration
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/modules/selected_rows.md
  Design Doc: Selected Rows
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/design/modules/op_documentation/net_op_design.md
  Network Design
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/design/modules/op_documentation/batch_norm_op.md
  批归一化

fluid系统形态 doc/fluid/design/system

待定

多语言接口 doc/fluid/design/interface

https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/interface/00.why_plain_c.md
Paddle多语言接口实现

https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/interface/01.inference_implementation.md
C-API 模型推断实现文档

分布式训练 doc/fluid/design/dist_train

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/dist_train/distributed_architecture.md
  Design Doc: Fluid Distributed Training Architecture
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/dist_train/distributed_lookup_table_design.md
  Design Doc: Distributed Lookup Table Operator
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/dist_train/multi_cpu.md
  Design Doc: Execute the Program with Multi CPU
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/dist_train/parameter_server.md
  Design Doc: Parameter Server

Others doc/fluid/design/others

-https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/others/gan_api.md
gan 这是一篇v2的文档，但此功能在v2没有实现，fluid可能会有这个功能，在写文档时可能会参考此文档

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/others/graph_survey.md
  Survey on Graph 一篇调研
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/others/graph.md
  Design Doc: Computations as a Graph 一篇不太完善的文档
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/others/parameters_in_cpp.md
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/others/simple_op_design.md
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/others/auto_gradient_check.md
  Auto Gradient Check Design

进阶使用 doc/fluid/howto

性能分析与调优 doc/fluid/howto/performance

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/howto/error_clip.md
  Error Clip 作者给出翻译“误差截断”
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/howto/profiler.md
  profiler

第三方库 doc/fluid/howto/third_party

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/howto/third_party/paddle_nccl.md
  Design Doc: NCCL support in Paddle Fluid
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/howto/third_party/mkldnn_fluid.md
  Design Doc: Add MKLDNN Kernel in Fluid Operator

开发标准 doc/fluid/dev

• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/dev/support_new_device.md
  Design Doc: Supporting new Device/Library
• https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/dev/releasing_process.md
  PaddlePaddle发行规范 若放在官网里 可以命名为“如何发布版本”
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/dev/name_convention.md
  operator参数命名规范
• https://github.com/PaddlePaddle/Paddle/tree/develop/doc/fluid/dev/op_markdown_format.md
  Operators标准md格式