[Docs] add Chinese version of compatibility.md (#172)

* [Docs] add Chinese version of compatibility.md

* [Docs] fix typo

* [Docs] fix lint

* [Docs] fix typo

* [Docs] fix typo

README_zh-CN.md

@@ -46,7 +46,7 @@ MMSelfSup **v0.5.0** 在 16/12/2021 发版.
 
 请参考 [changelog.md](docs/zh_cn/changelog.md) 获取更多细节和历史版本信息。
 
-MMSelfSup 和 OpenSelfSup 的不同点写在 [compatibility.md](docs/en/compatibility.md) 当中。
+MMSelfSup 和 OpenSelfSup 的不同点写在 [compatibility.md](docs/zh_cn/compatibility.md) 当中。
 
 ## 模型库和基准测试
 

docs/en/compatibility.md

@@ -24,11 +24,11 @@ In addition, this part is still under refactoring, it will be released in follow
 
 ### Models
 
-- The registry mechanism is updated. Currently, the parts under the `models` folder are built with a parent called MMCV_MODELS that is imported from `MMCV`. Please check [mmselfsup/models/builder.py](https://github.com/open-mmlab/mmselfsup/blob/master/mmselfsup/models/builder.py) and refer to [mmcv/utils/registry.py](https://github.com/open-mmlab/mmcv/blob/master/mmcv/utils/registry.py) for more details.
+- The registry mechanism is updated. Currently, the parts under the `models` folder are built with a parent called `MMCV_MODELS` that is imported from `MMCV`. Please check [mmselfsup/models/builder.py](https://github.com/open-mmlab/mmselfsup/blob/master/mmselfsup/models/builder.py) and refer to [mmcv/utils/registry.py](https://github.com/open-mmlab/mmcv/blob/master/mmcv/utils/registry.py) for more details.
 
-- The `models` folder includes algorithms, backbones, necks, heads, memories and some required utils. The `algorithms` integrates the other main components to build the self-supervised learning algorithms, which is like `classifiers` in MMCls or `detectors` in MMDet.
+- The `models` folder includes `algorithms`, `backbones`, `necks`, `heads`, `memories` and some required utils. The `algorithms` integrates the other main components to build the self-supervised learning algorithms, which is like `classifiers` in `MMCls` or `detectors` in `MMDet`.
 
-- In OpenSelfSup, the names of necks are kind of confused and all in one file. Now, the necks are refactored, managed with one folder and renamed for easier understanding. Please check `mmselfsup/models/necks` for more details.
+- In OpenSelfSup, the names of `necks` are kind of confused and all in one file. Now, the `necks` are refactored, managed with one folder and renamed for easier understanding. Please check `mmselfsup/models/necks` for more details.
 
 ## Codebase Conventions
 
@@ -42,7 +42,7 @@ MMSelfSup renews codebase conventions as OpenSelfSup has not been updated for so
 
   - One algorithm name has been modified: MOCO -> MoCo
 
-  - As all models' components inherit `BaseModule` from `MMCV`, the models are initialized with `init_cfg`. Please use it to set your initialization.
+  - As all models' components inherit `BaseModule` from `MMCV`, the models are initialized with `init_cfg`. Please use it to set your initialization. Besides, `init_weights` can also be used.
 
   - Please use new neck names to compose your algorithms, check it before write your own configs.
 

docs/zh_cn/compatibility.md

@@ -0,0 +1,59 @@
+# MMSelfSup 和 OpenSelfSup 的不同点
+
+该文件记录了最新版本 MMSelfSup 和 旧版以及 OpenSelfSup之间的区别。
+
+MMSelfSup 进行了重构并解决了许多遗留问题，它与 OpenSelfSup 并不兼容，如旧的配置文件需要更新，因为某些类或组件的名称已被修改。
+
+主要的不同点为：代码库约定，模块化设计。
+
+## 模块化设计
+
+为了构建更加清晰的目录结构， MMSelfSup 重新设计了一些模块。
+
+### 数据集
+
+- MMSelfSup 合并了部分数据集，减少了冗余代码.
+
+  - Classification, Extraction, NPID -> OneViewDataset
+
+  - BYOL, Contrastive -> MultiViewDataset
+
+- 重构了 `data_sources` 文件夹，现在的数据读取函数更加鲁棒。
+
+另外，该部分仍然在重构中，会在接下里的某一版本中发布。
+
+### 模型
+
+- 注册机制已经更新。 现在，`models` 文件夹下的各部分在构建时会有一个从 `MMCV` 中引入的父类 `MMCV_MODELS`。请查阅 [mmselfsup/models/builder.py](https://github.com/open-mmlab/mmselfsup/blob/master/mmselfsup/models/builder.py) 和 [mmcv/utils/registry.py](https://github.com/open-mmlab/mmcv/blob/master/mmcv/utils/registry.py) 获取更多信息。
+
+- `models` 文件夹包含 `algorithms`，`backbones`，`necks`，`heads`，`memories` 和一些所需的工具。`algorithms` 部分集成了其他主要的组件来构建自监督学习算法，就像 `MMCls` 中的 `classifiers` 或者 `MMDet` 中的 `detectors`。
+
+- 在 OpenSelfSup 中，`necks` 的命名会有一些混乱并且实现在同一个 python 文件中。现在，`necks` 部分已经被重构，通过一个文件进行归类管理，并进行重新命名。请查阅 `mmselfsup/models/necks` 获取更多信息。
+
+## 代码库约定
+
+由于 OpenSelfSup 很久没有更新，MMSelfSup 更新了代码库约定。
+
+### 配置文件
+
+- MMSelfSup 对所有配置文件进行了重命名，并制定了命名规范，请查阅 [0_config](./tutorials/0_config.md) 获取更多信息。
+
+- 在配置文件中，一些类的参数命名或组件名字已被修改。
+
+  - 一个算法名被修改： MOCO -> MoCo
+
+  - 由于所有模型的组件继承自 `MMCV` 的 `BaseModule`，模型根据 `init_cfg` 进行初始化。请您依照该规范进行初始化设置，`init_weights` 仍然适用。
+
+  - 请使用新的 necks 的命名来组合算，请在写配置文件前确认。
+
+  - 归一化层通过 `norm_cfg` 进行管理。
+
+### 脚本
+
+- `tools` 的目录结构被修改，现在更加清晰，通过多个文件夹进行脚本分类和管理。 例如，两个转换文件夹分为为了模型和数据格式。 另外，和基准测试相关的脚本都在 `benchmarks` 文件夹中，它和 `configs/benchmarks` 拥有相同的目录结构。
+
+- `train.py` 脚本中的参数已被更新， 两个主要修改点为
+
+  - 增加 `--cfg-options` 参数，通过命令行传参对配置文件进行修改。
+
+  - 移除 `--pretrained`， 通过 `--cfg-options` 设置预训练模型。