[Mistral] Mistral-7B-v0.1 support (#26447)

* [Mistral] Mistral-7B-v0.1 support

* fixing names

* slightly longer test

* fixups

* not_doctested

* wrongly formatted references

* make fixuped

---------

Co-authored-by: Timothee Lacroix <t@eugen.ai>
Co-authored-by: timlacroix <t@mistral.ai>

docs/source/en/_toctree.yml

@@ -384,6 +384,8 @@
         title: MegatronBERT
       - local: model_doc/megatron_gpt2
         title: MegatronGPT2
+      - local: model_doc/mistral
+        title: Mistral
       - local: model_doc/mluke
         title: mLUKE
       - local: model_doc/mobilebert