added module docstring

https://github.com/fphammerle/free-disk/commit/e9183309a9b795b37fa885a4cd932c985c143a86

freesurfer_volume_reader/__init__.py

@@ -1,3 +1,9 @@
+"""
+Read hippocampal subfield volumes computed by Freesurfer
+
+https://surfer.nmr.mgh.harvard.edu/fswiki/HippocampalSubfields
+"""
+
 import argparse
 import os
 import re
@@ -59,9 +65,7 @@ def read_hippocampal_volume_file_dataframe(volume_file_path: str) -> pandas.Data
 
 
 def main():
-    argparser = argparse.ArgumentParser(
-        description='Read hippocampal subfield volumes computed by Freesurfer'
-                    '\nhttps://surfer.nmr.mgh.harvard.edu/fswiki/HippocampalSubfields')
+    argparser = argparse.ArgumentParser(description=__doc__)
     argparser.add_argument('--filename-regex', dest='filename_pattern',
                            default=DEFAULT_HIPPOCAMPAL_VOLUME_FIND_FILENAME_PATTERN,
                            help='default: %(default)s')