Add llms subdir + update README (#145)

* add llms subdir + update README

* nits

* use same pre-commit as mlx

* update readmes a bit

* format

.pre-commit-config.yaml

@@ -1,5 +1,11 @@
 repos:
--   repo: https://github.com/psf/black
+-   repo: https://github.com/psf/black-pre-commit-mirror
     rev: 22.10.0
     hooks:
     -   id: black
+-   repo: https://github.com/pycqa/isort
+    rev: 5.12.0
+    hooks:
+    -   id: isort
+        args:
+            - --profile=black