Add list of stations to repos

[veenstrajelmer]

The netcdf files retrieved when downloading the GTSMip reanalysis dataset on CDS (C3S project) contain only station x/y coordinates, but no station names. This is quite inconvenient if a user wants to do subsetting by name (or coastal/regular), or just would like to see the waterlevel in Aburatsu or any other arbitrary actual station. Adding the xyn file from the SVN repos seemed the easiest way to work around this. However, the list of stations is different since some stations were dropped in the post-processing. A correct station list would provide a useful addition to the dataset on CDS, that supports easier spatial subsetting.

Todo:

• find the xynfile/csv that has the same length as the station dimension in the netcdf files
• backup option: manual version by @Tammo-Zijlker-Deltares at p:\archivedprojects\11208614-de-370a\00_general_data\DFLOWFM\GTSM_reference_timeseries\available_stations_obs.xyn
• host it on this repos
• while we are at it, also update the temporal extend in the readme from 2018 to 2024

[n-aleksandrova]

The list of stations was added at:
https://github.com/VU-IVM/gtsm3-era5-nrt/blob/main/04_supplementary_data/GTSM_output_locations_list.xyn

The script that was used to retrieve this list and cross-check the coordinates is located here:
p:\11210221-gtsm-reanalysis\GTSM-ERA5-E_dataset\scripts\GTSM_ERA5_get_output_stations.ipynb