text: Title: Custom labels for get_topic_tree
  Body: ### Discussed in https://github.com/MaartenGr/BERTopic/discussions/2122
  
  <div type='discussions-op-text'>
  
  <sup>Originally posted by **clfkenny** August 17, 2024</sup>
  Hi there, I noticed the `visualize_hierarchy` method has a `custom_labels` parameter. Is there anything similar to this for the `get_topic_tree` method? I use the LLM generated labels as the custom labels so the hierarchy tree is much easier to interpret. Thanks! </div>
  
  This seems like a good first issue for someone wanting to contribute to this repository. It has a very similar structure to the `visualize_hierarchy` functionality, so I believe it should be straightforward to implement. Unfortunately, I have a large backlog and cannot prioritize this, so if anyone wants to help out then that would be great!