Add CvT (#17299)

* Adding cvt files

* Adding cvt files

* changes in init file

* Adding cvt files

* changes in init file

* Style fixes

* Address comments from code review

* Apply suggestions from code review

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Format lists in docstring

* Fix copies

* Apply suggestion from code review

Co-authored-by: AnugunjNaman <anugunjjha@gmail.com>
Co-authored-by: Ayushman Singh <singhayushman13@protonmail.com>
Co-authored-by: Niels Rogge <nielsrogge@Nielss-MacBook-Pro.local>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

docs/source/en/_toctree.yml

@@ -192,6 +192,8 @@
       title: CPM
     - local: model_doc/ctrl
       title: CTRL
+    - local: model_doc/cvt
+      title: CvT
     - local: model_doc/data2vec
       title: Data2Vec
     - local: model_doc/deberta