[Docs] Fix typo in registry.md (#1717)

docs/en/understand_mmcv/registry.md

@@ -91,7 +91,7 @@ CONVERTERS = Registry('converter', build_func=build_converter)
 ```{note}
 In this example, we demonstrate how to use the `build_func` argument to customize the way to build a class instance.
 The functionality is similar to the default `build_from_cfg`. In most cases, default one would be sufficient.
-`build_model_from_cfg` is also implemented to build PyTorch module in `nn.Sequentail`, you may directly use them instead of implementing by yourself.
+`build_model_from_cfg` is also implemented to build PyTorch module in `nn.Sequential`, you may directly use them instead of implementing by yourself.
 ```
 
 ### Hierarchy Registry

docs/zh_cn/understand_mmcv/registry.md

@@ -86,7 +86,7 @@ CONVERTERS = Registry('converter', build_func=build_converter)
 该功能类似于默认的`build_from_cfg`。在大多数情况下，默认就足够了。
 ```
 
-`build_model_from_cfg`也实现了在`nn.Sequentail`中构建PyTorch模块，你可以直接使用它们。
+`build_model_from_cfg`也实现了在`nn.Sequential`中构建PyTorch模块，你可以直接使用它们。
 
 ### 注册器层结构