[example] update GPT README (#2095)

examples/language/gpt/README.md

@@ -1,15 +1,52 @@
-## Overview
-This example shows how to use Colossal-AI to run huggingface GPT training in distributed manners.
+# Train GPT with Colossal-AI
+
+This example shows how to use [Colossal-AI](https://github.com/hpcaitech/ColossalAI) to run huggingface GPT training in distributed manners.
 
 ## GPT
-We use the GPT2 model from huggingface transformers. The input data is randonly generated.
-The `train_gpt_demo.py` provides three distributed plans, i.e. ColossalAI, PyTorch DDP and ZeRO.
-The ColossalAI leverages Tensor Parallel and Gemini.
 
-## Quick Start
-You can launch training by using the following bash script.
+We use the [GPT-2](https://huggingface.co/gpt2) model from huggingface transformers. The key learning goal of GPT-2 is to use unsupervised pre-training models to do supervised tasks.GPT-2 has an amazing performance in text generation, and the generated text exceeds people's expectations in terms of contextual coherence and emotional expression.
+
+## Requirements
+
+Before you can launch training, you need to install the following requirements.
+
+### Install PyTorch
+
+```bash
+#conda
+conda install pytorch==1.12.0 torchvision==0.13.0 torchaudio==0.12.0 cudatoolkit=11.3 -c pytorch
+#pip
+pip install torch==1.12.0+cu113 torchvision==0.13.0+cu113 torchaudio==0.12.0 --extra-index-url https://download.pytorch.org/whl/cu113
+```
+
+### Install [Colossal-AI v0.1.11rc5](https://colossalai.org/download/) From Official Website
+
+```bash
+pip install colossalai==0.1.11rc5+torch1.12cu11.3 -f https://release.colossalai.org
+```
+
+### Install transformers
+
+```bash
+pip install transformers
+```
+
+This is just an example that we download PyTorch=1.12.0, CUDA=11.6 and colossalai=0.1.11rc5+torch1.12cu11.3. You can download another version of PyTorch and its corresponding ColossalAI version. Just make sure that the version of ColossalAI is at least 0.1.10, PyTorch is at least 1.8.1 and transformers is at least 4.231.
+
+## Dataset
+
+For simplicity, the input data is randonly generated here.
+
+## Training
 
 ```bash
-pip install -r requirements.txt
 bash run.sh
 ```
+
+### Training config
+
+The `train_gpt_demo.py` provides three distributed plans, you can choose the plan you want in `run.sh`. The Colossal-AI leverages Tensor Parallel and Gemini + ZeRO DDP.
+
+- Colossal-AI
+- PyTorch DDP
+- ZeRO