1.1. will not only allow you to search for text within a definition, it will also allow you to just search for any definition. As an example, you could search all your iCloud sheets for images. Or, as a more interesting use case, you could search your novel or thesis for annotations.
Since this is based on our semantics engine, Search will find the definitions regardless of the markup used in your sheets. So no need to search for, say, “###”, if you’re looking for that perfect Header 3.