Add llms subdir + update README (#145)

* add llms subdir + update README

* nits

* use same pre-commit as mlx

* update readmes a bit

* format

llms/mistral/convert.py

@@ -0,0 +1,32 @@
+# Copyright © 2023 Apple Inc.
+
+import argparse
+import json
+from pathlib import Path
+
+import numpy as np
+import torch
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Convert Mistral weights to MLX.")
+    parser.add_argument(
+        "--model_path",
+        type=str,
+        default="mistral-7B-v0.1/",
+        help="The path to the Mistral model. The MLX weights will also be saved there.",
+    )
+    args = parser.parse_args()
+
+    model_path = Path(args.model_path)
+    state = torch.load(str(model_path / "consolidated.00.pth"))
+    np.savez(
+        str(model_path / "weights.npz"),
+        **{k: v.to(torch.float16).numpy() for k, v in state.items()}
+    )
+
+    # Save config.json with model_type
+    with open(model_path / "params.json", "r") as f:
+        config = json.loads(f.read())
+        config["model_type"] = "mistral"
+    with open(model_path / "config.json", "w") as f:
+        json.dump(config, f, indent=4)