Update README.md

README.md

@@ -95,10 +95,10 @@ everything needed end-to-end.
 
 ## Usage
 
-The decoder checkpoints are loaded by the inference scripts in the PiD
-codebase. The exact `(backbone, ckpt_type) → path` mapping is the single source
+The decoder checkpoints are loaded by the inference scripts in the [PiD
+codebase](https://github.com/nv-tlabs/pid). The exact `(backbone, ckpt_type) → path` mapping is the single source
 of truth in
-[`pid/_src/inference/checkpoint_registry.py`](https://github.com/) — clone the
+[`pid/_src/inference/checkpoint_registry.py`](https://github.com/nv-tlabs/PiD/blob/main/pid/_src/inference/checkpoint_registry.py) — clone the
 repo, point it at this snapshot, and the demos pick the right file
 automatically: