Update README.md

Annotate the code blocks.

README.md

@@ -10,7 +10,7 @@ This repository is the official implementation of [My awesome paper title](https
 
 To install requirements:
 
-```
+```setup
 pip install -r requirements.txt
 ```
 
@@ -20,7 +20,7 @@ pip install -r requirements.txt
 
 To train the model in the paper, run this command:
 
-```
+```train
 python train.py --input-data <path_to_data> --alpha 10 --beta 20
 ```
 
@@ -30,7 +30,7 @@ python train.py --input-data <path_to_data> --alpha 10 --beta 20
 
 To evaluate my model on ImageNet, run:
 
-```
+```eval
 python eval.py --model-file mymodel.pth --benchmark imagenet
 ```