add PaLM link (#704)

* add PaLM link

README.md

@@ -33,6 +33,7 @@
      <li><a href="#GPT-3">GPT-3</a></li>
      <li><a href="#GPT-2">GPT-2</a></li>
      <li><a href="#BERT">BERT</a></li>
+     <li><a href="#PaLM">BERT</a></li>
    </ul>
  </li>
 
@@ -96,6 +97,9 @@ distributed training in a few lines.
 
 - 2x faster training, or 50% longer sequence length
 
+### PaLM
+- [PaLM-colossalai](https://github.com/hpcaitech/PaLM-colossalai): Scalable implementation of Google's Pathways Language Model ([PaLM](https://ai.googleblog.com/2022/04/pathways-language-model-palm-scaling-to.html)).
+
 Please visit our [documentation and tutorials](https://www.colossalai.org/) for more details.
 
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