Improve documentation of select for tabulator widget

[leoffj]

In version 0.11 the selection options of the tabulator widget are described as follows:

selectable = param.ObjectSelector(default=True, objects=[True, False, ‘checkbox’])

Whether a table’s rows can be selected or not. Multiple selection is allowed and can be achieved by either clicking multiple checkboxes (if enabled) or using Shift + click on rows.

This does not cover all possibilities of the tabulator widget and the description text is a bit misleading.

Is your feature request related to a problem? Please describe.

I described my problem in https://discourse.holoviz.org/t/selecting-only-one-row-in-tabulator-widget/1953?u=jleoff. In short, I want only one row of the tabulator widget to be selectable at once (the table contains the input for a plot, you select what you want to see). The solution is actually very easy, just set selectable = 1. I did waste quite some time to find this solution though, as I was mislead by the documentation. The documentation of tabulator does show this possibility.

Describe the solution you'd like

Please update the documentation. It would probably be best to reference the original documentation? For reference, this is the current documentation at http://tabulator.info/docs/4.2/select

The selectable option can take one of a several values:

false - selectable rows are disabled
true - selectable rows are enabled, and you can select as many as you want
integer - any integer value, this sets the maximum number of rows that can be selected (when the maximum number of selected rows is exeded, the first selected row will be deselected to allow the next row to be selected).
"highlight" (default) - rows have the same hover stylings as selectable rows but do not change state when clicked. This is great for when you want to show that a row is clickable but don't want it to be selectable.