Add Cohere2 docs details (#35294)
* Add Cohere2 docs details
* Update docs/source/en/model_doc/cohere2.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
---------
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
