Update README

README.md

@@ -16,18 +16,17 @@ simple Python model of a C++ translation unit.
 
 ## Limitations
 
-Currently `clang.cindex.Config.set_library_path()` must be called before
-attempting to load a translation unit. This is because the libclang shared
-library is not in a standard location. This may be fixed in the future.
+Currently the environment variable `PY_CPPMODEL_LIBCLANG_PATH` must be defined
+to specify where libclang can be found. This may be fixed in the future.
 
 ## Testing
 
 To run the tests, run:
 
 ```sh
-python3 -m venv .venv           # Create a Python virtual env
+python3 -m venv .venv           # Create a Python virtual env.
 source ./.venv/bin/activate     # Activate the virtual env for bash by source.
 
-mypy *.py --check-untyped-defs  # Run mypy to check type hints
-unittest discover .             # Run tests
+mypy *.py --check-untyped-defs  # Run mypy to check type hints.
+unittest discover .             # Run tests.
 ```