Add llama3 (#30334)

* nuke

* add co-author

* add co-author

* update card

* fixup and fix copies to please our ci

* nit fixup

* super small nits

* remove tokenizer_path from call to `write_model`

* always safe serialize by default

---------

Co-authored-by: pcuenca <pcuenca@users.noreply.github.com>
Co-authored-by: xenova <xenova@users.noreply.github.com>

docs/source/en/_toctree.yml

@@ -394,6 +394,8 @@
         title: LLaMA
       - local: model_doc/llama2
         title: Llama2
+      - local: model_doc/llama3
+        title: Llama3
       - local: model_doc/longformer
         title: Longformer
       - local: model_doc/longt5