docs: update

docs/en/installation/install_paddleclas_en.md

@@ -23,7 +23,13 @@ git clone https://gitee.com/paddlepaddle/PaddleClas.git -b develop
 
 <a name='2'></a>
 
-## 2. Install requirements
+## 2. Install PaddleClas and requirements
+
+It is recommanded that installing from PyPI:
+
+```shell
+pip install paddleclas
+```
 
 PaddleClas dependencies are listed in file `requirements.txt`, you can use the following command to install the dependencies.
 

docs/zh_CN/installation/install_paddleclas.md

@@ -88,7 +88,13 @@ git clone https://gitee.com/paddlepaddle/PaddleClas.git -b release/2.4
 ```
 <a name='3'></a>
 
-### 3. 安装 Python 依赖库
+### 3. 安装 PaddleClas 及其 Python 依赖库
+
+建议直接从 PyPI 安装 PaddleClas：
+
+```shell
+pip install paddleclas
+```
 
 PaddleClas 的 Python 依赖库在 `requirements.txt` 中给出，可通过如下命令安装：