Fix println in morph_targets example (#15851)

# Objective

This example uses `println` from a system, which we don't advise people
do. It also gives no context for the debug prints, which I assumed to be
stray debug code at first.

## Solution

Use `info!`, and add a small amount of context so the console output
looks deliberate.

## Testing

`cargo run --example morph_targets`

examples/animation/morph_targets.rs

@@ -103,8 +103,10 @@ fn name_morphs(
  let Some(names) = mesh.morph_target_names() else {
  return;
  };
+
+ info!("Target names:");
  for name in names {
- println!(" {name}");
+ info!(" {name}");
  }
  *has_printed = true;
 }