Remove descriptive echo statement from transcription example

- Remove the 'Transcribing audio with custom model...' output message
- Keep the example focused on the core functionality without extra output

Author: OskarStark

examples/openai/additional-model.php

@@ -47,7 +47,6 @@
     ),
 );
 
-echo "Transcribing audio with custom model 'gpt-4o-mini-transcribe':\n";
 $result = $platform->invoke($transcribeModel, $messages, [
     'max_tokens' => 300,
 ]);