add <!--more--> tag to tutorial 1

Author: njzjz

source/_posts/tutorial1.md

@@ -16,7 +16,7 @@ A[Prepare data] --> B[Training]
 B --> C[Freeze the model]
 {% endmermaid %}
 
-What? Only three steps? Yes, it's that simple. Preparing data is converting the computational results of DFT to data that can be recognized by the DeePMD-kit. Training is train a Deep Potential model using the DeePMD-kit with data prepared in the previous step. Finally, what we need to do is to freeze the restart file in the training process into a model, in other words is to extract the neural network parameters into a file for subsequent use. I believe you can't wait to get started. Let's go!
+What? Only three steps? Yes, it's that simple.<!--more--> Preparing data is converting the computational results of DFT to data that can be recognized by the DeePMD-kit. Training is train a Deep Potential model using the DeePMD-kit with data prepared in the previous step. Finally, what we need to do is to freeze the restart file in the training process into a model, in other words is to extract the neural network parameters into a file for subsequent use. I believe you can't wait to get started. Let's go!
 
 The data format of the DeePMD-kit is introduced in the [official document](https://deepmd.readthedocs.io/) but seems complex. Don't worry, I'd like to introduce a data processing tool: dpdata! You can use only one line Python scripts to process data. So easy!