docs(geometry/edit): document Recordable

src/geometry/edit.rs

@@ -89,6 +89,10 @@ impl<
     }
 }
 
+/// Recordable objects are objects to which a [recorder](`GeometryEdit`) can be attached,
+/// the specialized methods working on `&mut` [`Recording`] then (are to be expected to)
+/// also write changes to the passed `recorder`, and can also be replayed or rolled back
+/// via [`ApplyGeometryEdit`].
 pub trait Recordable {
     type PW: GetWidth
         + GetLayer