update README

README.md

@@ -29,10 +29,12 @@ new_data = rechunk_dataset(dset)
 ### Using the command line interface:
 
 ```bash
-rechunk-data  --help                   
-usage: rechunk-data [-h] [-o OUTPUT] [--netcdf-engine {h5netcdf,netcdf4}] [--skip-cf-convention] [--force-horizontal] [--check-chunk-size] [-v] [-V] input
+rechunk-data --help                                
+usage: rechunk-data [-h] [-o OUTPUT] [--netcdf-engine {h5netcdf,netcdf4}] [--size SIZE] [--auto-chunks] [--skip-cf-convention] [--force-horizontal] [--check-chunk-size]
+                    [-v] [-V]
+                    input
 
-Rechunk input netcdf data to optimal chunk-size. approx. 126 MB per chunk
+Rechunk input netcdf data to optimal chunk-size. approx. 126 MB per chunk. By default it only optimises time.
 
 positional arguments:
   input                 Input file/directory. If a directory is given all ``.nc`` files in all sub directories will be processed
@@ -43,6 +45,8 @@ options:
                         ``input`` is overridden. (default: None)
   --netcdf-engine {h5netcdf,netcdf4}
                         The netcdf engine used to create the new netcdf file. (default: netcdf4)
+  --size, -s SIZE       Specify chunk-size (in MiB). (default: None)
+  --auto-chunks, -ac    Allow Dask to determine optimal chunk sizes for all dimensions. (default: False)
   --skip-cf-convention  Do not assume assume data variables follow CF conventions. (default: False)
   --force-horizontal, -fh
                         Force horizontal chunking (~126 MB per chunk). (default: False)