docs: simplify radas instructions

docs/doc_sources/Usage.rst

@@ -11,21 +11,18 @@ The cfspopcon package is available on the `Python Package Index <https://pypi.or
 .. code::
 
   >>> pip install cfspopcon
-
 .. warning::
-   The :code:`cfspopcon.atomic_data` module requires data files produced by the `radas project <https://github.com/cfs-energy/radas>`_. Radas produces these files by processing `OpenADAS <https://open.adas.ac.uk/adf11>`_ data. These files are not shipped as part of :code:`cfspopcon`. Follow the below steps after the :code:`pip install cfspopcon` command (we will try to make this smoother in the future. N.b. this only has to be done once).
+   The :code:`cfspopcon.atomic_data` module requires data files produced by the `radas project <https://github.com/cfs-energy/radas>`_. Radas produces these files by processing `OpenADAS <https://open.adas.ac.uk/adf11>`_ data. These files are not shipped as part of :code:`cfspopcon`, thus the below steps need to be run once after installing :code:`cfspopcon`. Please follow the below instructions from within the python environement :code:`cfspopcon` is installed into.
 
    .. code:: bash
-     
+
     >>> export RADAS=$(python -c "from cfspopcon import atomic_data;from pathlib import Path; print(Path(atomic_data.__file__).parent)")
-    >>> pushd /tmp
     >>> git clone https://github.com/cfs-energy/radas.git
     >>> pushd radas
-    >>> poetry install --only main
-    >>> poetry run fetch_adas
-    >>> poetry run run_radas
+    >>> PYTHONPATH=$PWD:$PYTHONPATH python adas_data/fetch_adas_data.py
+    >>> PYTHONPATH=$PWD:$PYTHONPATH python run_radas.py
     >>> cp ./cases/*/output/*.nc $RADAS
-    >>> popd && popd
+    >>> popd
 
 
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