seviri l1b native satpy converter

src/satpy/README.md

@@ -0,0 +1,12 @@
+# Satpy converter setup guide
+
+The `ioda-converter/src/satpy` directory contains IODA converters that use the ([Satpy](https://satpy.readthedocs.io/en/stable/index.html)) python library.  To use these converters it is asssumed one can build ioda-converters:
+- Use ([spack-stack](https://jointcenterforsatellitedataassimilation-jedi-docs.readthedocs-hosted.com/en/latest/using/jedi_environment/spackbuild.html)) environment
+- Have a python virtual environment created via:  `python3 -m venv --system-site-packages venv` followed by `source venv/bin/activate`
+
+If one has these prerequisites they can proceed to install satpy into that virtual environment
+
+## Configuration Guide
+
+**satpy**
+   - Recommend [pip install](https://satpy.readthedocs.io/en/stable/install.html#pip-based-installation) to virtual environment