pyic_view: Improve documentation.

scripts/pyic_view.py

@@ -782,10 +782,21 @@ def main():
     help_text = """
     Opens an interactive GUI to visualize horizontal ICON data.
 
+    pyic_view can process data on the native ICON grid or HEALPix. For data on
+    the native grid, it requires ckdtrees. These ckdtrees are looked for either
+    in a directory specified by the `--path_grid` option or in 
+    `pyicon/pyicon/params_user.json`.
+
     Usage notes:
     ------------
-    Basic usage:
-    pyic_view.py netcdf_file_or_list.nc [options]
+    Open one netcdf file:
+    pyic_view icon_data_20000101T000000Z.nc
+    
+    Use any sort of wildcarts:
+    pyic_view icon_data_20000101T*.nc 
+
+    Open zarr archive:
+    pyic_view icon_zarr_archive.zarr
 
     Argument list:
     --------------