Update docs for dynamic loading of libpython (#101)

BUG=https://b.corp.google.com/issues/322386436

Co-authored-by: Chunnien Chan <[email protected]>

README.md

@@ -102,6 +102,17 @@ Alternately, the nightly version can be installed with:
 pip install ai-edge-torch-nightly
 ```
 
+### Update LD_LIBRARY_PATH if necessary
+
+Torch XLA builds a shared library, `_XLAC.so` that needs to link to the version of Python
+it was built with (currently 3.10 or 3.11). In order to ensure that `import _XLAC` can succeed,
+update the LD_LIBRARY_PATH to the lib directory of your Python environment:
+
+```bash
+export LD_LIBRARY_PATH=<path to Python installation>/lib:$LD_LIBRARY_PATH
+```
+
+
 * The list of versioned releases can be seen [here](https://github.com/google-ai-edge/ai-edge-torch/releases).
 * The full list of PyPi releases (including nightly builds) can be seen [here](https://pypi.org/project/ai-edge-torch/#history).