[Whisper Docs] Nits
# What does this PR do?
Adresses #24342, where it is mentioned that the documentation is conter intuitive. Indeed, after a lot of changes, the default value for the `bos_token` that we use is different, thus no official models (hosted on the hub) use `bos_token = "<startoftranscript>"`
_The documentation is not available anymore as the PR was closed or merged._