Update Readme with URL options

[jameshalgren]

The Readme would be more clear with the baseurlinput options. This could be added below the runinput options.

- `urlbaseinput`: An integer selecting the overall data source. Options include:
  - 0: "",  # Empty
  - 1: "https://nomads.ncep.noaa.gov/pub/data/nccf/com/nwm/prod/",  # NOAA hosted operational output
  - 2: "https://nomads.ncep.noaa.gov/pub/data/nccf/com/nwm/post-processed/WMS/",  # not functioning
  - 3: "https://storage.googleapis.com/national-water-model/",  # authenticated access to Google buckets
  - 4: "https://storage.cloud.google.com/national-water-model/",  # open-access to Google buckets
  - 5: "gs://national-water-model/",  
  - 6: "gcs://national-water-model/",
  - 7: "https://noaa-nwm-pds.s3.amazonaws.com/",  # 4 week rolling AWS short range
  - 8: "https://ciroh-nwm-zarr-copy.s3.amazonaws.com/national-water-model/",  # operational Kerchunk json archive

[sepehrkrz]

README.md is updated with url options