Add build error solution

Author: Jessica Lin

README.md

@@ -27,3 +27,5 @@ In case you prefer to write your tutorial in jupyter, you can use [this script](
 
 - Then you can build using `make docs`. This will download the data, execute the tutorials and build the documentation to `docs/` directory. This will take about 60-120 min for systems with GPUs. If you do not have a GPU installed on your system, then see next step.
 - You can skip the computationally intensive graph generation by running `make html-noplot` to build basic html documentation to `_build/html`. This way, you can quickly preview your tutorial.
+
+- If you get **ModuleNotFoundError: No module named 'pytorch_sphinx_theme' make: *** [html-noplot] Error 2**, from /tutorials/src/pytorch_sphinx_theme run `python setup.py install`.