Wikibase disallows newlines within its string data type, so I think it would make sense to introduce a new data type for multi-line text.

This would be useful to add short example snippets to programming languages, markup languages as well as text-based file formats.

Such examples can currently only be added via images (with the commonsMedia data type) ... that is however inherently less accessible than plain text, especially to people with disabilities or visual impairments.