Add description to ProteinNet MSA script

scripts/prepare_proteinnet_msas.py

@@ -39,7 +39,9 @@ def main(args):
  
 
 if __name__ == "__main__":
-    parser = argparse.ArgumentParser()
+    parser = argparse.ArgumentParser(description=
+        "Converts raw ProteinNet MSAs into a format recognized by the parser"
+    )
     parser.add_argument(
         "msa_dir", type=str, help="Directory containing ProteinNet MSAs"
     )