doc: update Readme (#57)

* add notes for python version and mac installation

* add downloads counts

* move mac nots

Author: yanghan234

README.md

@@ -10,7 +10,7 @@
 
 [![arXiv](https://img.shields.io/badge/arXiv-2405.04967-blue?logo=arxiv&logoColor=white.svg)](https://arxiv.org/abs/2405.04967)
 [![Requires Python 3.9+](https://img.shields.io/badge/Python-3.9+-blue.svg?logo=python&logoColor=white)](https://python.org/downloads)
-
+[![PyPI Downloads](https://static.pepy.tech/badge/mattersim)](https://pepy.tech/projects/mattersim)
 </h4>
 
 
@@ -23,7 +23,8 @@ This README provides a quick start guide. For more comprehensive information, pl
 ## Installation
 
 ### Prerequisite
-* Python==3.9
+* `Python >= 3.9`
+
 
 ### Install from PyPI
 > [!TIP]
@@ -37,6 +38,7 @@ This README provides a quick start guide. For more comprehensive information, pl
 > conda activate mattersim
 > ```
 >
+> Although MatterSim can be installed with `Python > 3.9`, we recommend using `Python == 3.9` for optimal compatibility.
 
 To install MatterSim, use the following command. Please note that downloading the dependencies may take some time:
 ```bash
@@ -73,6 +75,9 @@ python setup.py build_ext --inplace
 
 ## Usage
 
+> [!TIP]
+> **Note for macOS Users:** If you are using macOS with Apple Silicon, please be aware of potential numerical instability with the MPS backend. We recommend using the CPU device for MatterSim on Mac to avoid these issues.
+
 ### A minimal test
 ```python
 import torch