GWHAT crash when importing a water level datafile with the wrong format

[jnsebgosselin]

What steps will reproduce the problem?

1. Try to import a water level datafile with the wrong format

Please provide any additional information below

[jnsebgosselin]

It would be a good idea to add a link in the doc in the plotting the hydrograph section to the section in the doc where the format of the water level datafile is described.

https://gwhat.readthedocs.io/en/latest/plotting_hydrograph.html
https://gwhat.readthedocs.io/en/latest/manage_data.html#water-level-data-files

Also, it would be a good idea to add such a link directly in the GUI.