Remove tokenizers from the doc table
# What does this PR do?

As discussed offline with @LysandreJik and @stas00 it doesn't really make sense to have the info on tokenizers in this table in the index, which:
- makes it look like something is missing for vision models or speech models
- is not accurate when a model uses another's tokenizer model.

This PR removes it and only leaves the frameworks supported by each model.
_The documentation is not available anymore as the PR was closed or merged._