Date handling in docs is misleading

[kinverarity1]

Describe the bug This section of the documentation that illustrates how lasio handles date and/or timestamps by default is misleading: https://lasio.readthedocs.io/en/v0.30/data-section.html#handling-text-dates-timestamps-or-any-non-numeric-characters

To Reproduce The only reason this is handled well is because the date code has a letter adjacent to the hyphen e.g. 01-Jan-20. If it is an entirely numeric code, it does not work by default e.g. 2020-01-18 splits into new columns based on the hyphen, due to the default regexp substitutions.

Expected behavior The documentation should be more representative (pending a more comprehensive and appropriate default behaviour) e.g. show how to use the dtypes argument.

[kinverarity1]

Note #530 should fix the underlying error and therefore the documentation can remain unchanged