Document the multiline option for strings in user configurations

https://redmine.teklia.com/issues/7870
https://redmine.teklia.com/issues/9102

Requires arkindex/backend#1868 (closed) and arkindex/frontend#1511 (closed) (in Arkindex 1.7.1)

The docs on string user configuration parameters should mention that an optional multiline boolean attribute will show a larger text input that allows line breaks. Note that a string with line breaks in a regular input will still be allowed. There is no specific validation.

changed milestone to %Backlog

added Documentation P3 Quick Win labels

changed title from Document the multiline optino for strings in user configurations to Document the multiline option for strings in user configurations

changed the description

assigned to @mlbonhomme

mentioned in merge request !619 (merged)

closed with merge request !619 (merged)

changed milestone to %0.5.0