Generate tasks.json taxonomy from `huggingface_hub`
_The documentation is not available anymore as the PR was closed or merged._ Ok recomputed the json file, this should be ready to review now! @lhoestq  Note: the generated JSON from `hf/hub-docs` can be found in the output of a GitHub Action run on that repo, for instance in https://github.com/huggingface/hub-docs/runs/6006686983?check_suite_focus=true

(click on "Run export-tasks script") Should we not add the tasks with hideInDatasets? yes, probably true – i'll change that in a PR in `hub-docs` Yes that's good :) feel free to merge thanks to the both of you!