Clarify what "Sort by" on EntityReference field configuration form means

Patch works as advertised!

Would this slightly shorter description still be sufficiently descriptive?
"Select the field to be used to sort entity options."

(Needed reroll for 8.9.x because of #3089523: Use progressive disclosure to hide Sort options on entity reference fields until bundles are selected; please note: old version of patch still works on 8.8.x, until if/when #3089523 is backported!)

Attached: reroll for 8.9.x, and a plain diff of old/new versions of patch.

Coming up next: There's a little spelling typo ("refrenced"), but also, I agree that the language can be tightened just a bit, as @jwkovell mentioned in #3! Anyway, that'll be the next file -- wanted the reroll to have its own patch version so things don't get too confusing.

Mkay, revised language idea attached -- not much shorter haha, I went back and forth... (Also attached, an corresponding version for 8.8.x, based on #2.)

I *think* this version is clearer, but if folks prefer the original language, I can do a version that just fixes the typo and nothing else, just to help wrap things up!

Hm.

Adding a description to this field is definitely a good idea, in my opinion.

I'm not sure about the wording though. It brings up questions, like:
- Is this sort order followed for all widgets? (autocomplete, select, checkboxes, ...)
- Why isn't it an option on the widget anyway? It seems to be only relevant for the editing form, not for the field settings, so I don't actually understand why it is on the field settings in the first place.
- Is this option available when you select a View to determine the available entities, and if so, does it override the sort in the view?

And the proposed wording:
Select a field to use for sorting available entity options.

- Maybe get rid of "available"? I don't think that really adds anything to the description.
- Technically, it's not really just fields that are options here. For fields that have more than one attribute/value, such Image fields, you have the option to sort by each attribute, not to sort by the "field" as a whole (which wouldn't really make sense for an Image field anyway).
- I wonder why we don't choose a sensible default, which would be the label/title? I am pretty sure that is what would be shown to the user in lists of entity options, so it seems only sensible to default to putting what is shown in alphabetical order.

I realize that these questions probably go beyond the scope of this issue, but ... those are what occur to me when I look at this.

Patch failed to apply on 9.2.x.Needs reroll

Checking patch core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php...
error: while searching for:
      $form['sort']['field'] = [
        '#type' => 'select',
        '#title' => $this->t('Sort by'),
        '#options' => [
          '_none' => $this->t('- None -'),
        ] + $fields,

error: patch failed: core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php:145
error: core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php: patch does not apply

Rerolled patch #8.Please check it