Resource creation: "will be guessed automatically" tip lost for Format field

When creating a resource with ckanext-scheming 1.2.0, a field for the Format shows. When ckanext-scheming is not installed, a tip tells users "This will be guessed automatically. Leave blank if you wish". But when it is, this helpful tip does not show. It would be nice to keep it.

I did not verify that this persists in version 2, but by looking at \templates\package\snippets\resource_form.html I assume it does. The basic_fields block is overridden, and that tip is not included in ckanext-scheming.

I am not sure how to restore it given the way basic fields are handled:
```
{%- for field in schema.resource_fields -%}
{%- if field.form_snippet is not none -%}
{%- snippet 'scheming/snippets/form_field.html',
field=field, data=data, errors=errors,
entity_type='dataset', object_type=dataset_type -%}
{%- endif -%}
{%- endfor -%}
```

Start in templates/package/snippets/resource_form.html and compare the overridden basic_fields block with the default resource form behavior. Trace how schema.resource_fields and form_snippet are rendered through scheming/snippets/form_field.html. Done means the Format field again displays “This will be guessed automatically. Leave blank if you wish” when ckanext-scheming is installed.

Written by the indexing model from the issue text.