Update doc for default tone-mapper workflow

[Phemisters]

darktable PR: darktable-org/darktable#18547

Update the default in preferences for the workflow - I moved sigmoid up as it is the new default and that also makes the description order correspond to the order of the combo-box.

While doing this I noticed the white balance now has "as shot to reference" and for me that seems to be what it defaults to. That is why I updated the sentence about white balance, as I think it applies in the same way as for "camera reference". You may prefer we wait to do that change when darktable PR 15602 is done.

[elstoc]

Thanks. I will hold off merging this for now as I suspect we might need to make some other tweaks elsewhere in the doc to account for this. For example, while I'm not currently interested in changing the recommendations in the overview/workflow section (which suggests using filmic to process), it might still need some wording tweaks to account for the new default.

[Phemisters]

we might need to make some other tweaks

I'm not sure if you have a plan for this. I have had a go at some small updates for this, but happy to revert those or indeed close this PR until someone has the time and knowledge for a more thorough update.

[github-actions]

This pull request has not had any activity in the past 60 days and will be closed in 365 days if not updated. Please verify it has no conflicts with the master branch and rebase if needed. Please add a comment if you need help or give permission to other people to finish your work.