Documentation enhancement: Enhance documentation of 'table-column-type' for better use and quick finding

[buildersim21]

Hi,

The documentation in section 4.14, preamble-only options, talks about the option 'table-column-type' but does not provide a quick example of its use to reinforce its usage: such as is it usable only in \sisetup{} when in preamble or is a package option?

The need for this feature should be highlighted as I had to go far into the documentation to find this fix to my need for aspects of siunitx and the enhancements brought by packages that also load 'arraycols' now, which uses the default 'S' modifier of cellspace with no way of changing it. A brief mention of this under compatibility and/or SI for the impatient sections would be well placed for its quick finding and use by users of siunitx and arraycols. I had not considered that siunitx allowed a different column specifier than S. Quickly scanning the documentation, as, yes, I am impatient when I am setting up new documents, I hadn't noticed that one paragraph under "preamble-only options".

Thank you.

[josephwright]

This is quite a niche requirement, hence it doesn't really belong in the quick start guide. I'm happy though to think about how to make it a little easier to find.