Make the set_description API a bit nicer.

widgets/src/labeled_item/mod.rs

@@ -45,9 +45,10 @@ impl LabeledItem {
         self.inner().model.set_title(title)
     }
 
-    pub fn set_description<S>(&self, description: Option<S>)
+    pub fn set_description<S, O>(&self, description: O)
     where
         S: ToString,
+        O: Into<Option<S>>,
     {
         self.inner().model.set_description(description)
     }