Improve documentation of pooler_output in ModelOutput (#13228)
* update documentation of pooler_output in modeling_outputs, making it more clear and available for generic usage
* Update src/transformers/modeling_outputs.py
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
* Update src/transformers/modeling_outputs.py
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
* run make style
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>