Document multiple selection option for Select ingredient

[antwertinger]

Summary

Adds documentation for the new multiple setting on the Select ingredient that enables multiple value selection.

Changes

• Updated Select ingredient description to explain Array storage for multiple selections
• Added multiple: true setting documentation with default value
• Added two examples: single selection (default) and multiple selection
• Clarified that values are stored as String by default and as Array when multiple is enabled

Example Usage

- name: categories
  type: Select
  settings:
    select_values: ['Technology', 'Design', 'Marketing', 'Sales']
    multiple: true

[tvdeyen]

The value must be one of the values from select_values.

No, the value must not be one of the select_values. It can be any value.

[tvdeyen]

We need a note about the minor version this was introduced. 8.1 in this case

[tvdeyen]

@antwertinger also integrated in 8a59d18 now. Adjust if necessary