Add description/tooltip to table columns

Description of the limitation and why it is relevant to address

As a developer I want to add descriptions/tooltips to a table column so that users can get more information on what the column values should be, what it represents or to give more context.

I think this is relevant for the VIKTOR platform because it is already possible with all other fields, only the table does not allow this.

Submitter proposed design (optional)

Fields already allow for descriptions. The tooltip should only appear on the table.

Current workarounds

None

Requested by

@RamiEvans