Update README.md

Author: d4l3k

README.md

@@ -10,7 +10,10 @@ Easy Per Step Fault Tolerance for PyTorch
 </h3>
 
 <p align="center">
-| <a href="https://pytorch-labs.github.io/torchft/"><b>Documentation</b></a> | <a href="https://github.com/pytorch-labs/torchft/blob/main/media/fault_tolerance_poster.pdf"><b>Poster</b></a> |
+  | <a href="https://pytorch-labs.github.io/torchft/"><b>Documentation</b></a> 
+  | <a href="https://github.com/pytorch-labs/torchft/blob/main/media/fault_tolerance_poster.pdf"><b>Poster</b></a>
+  | <a href="https://docs.google.com/document/d/1OZsOsz34gRDSxYXiKkj4WqcD9x0lP9TcsfBeu_SsOY4/edit"><b>Design Doc</b></a>
+  |
 </p>
 
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