update readme

README.md

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-[![codecov](https://codecov.io/github/enigne/PINNICLE/graph/badge.svg?token=S7REK0IKJH)](https://codecov.io/github/enigne/PINNICLE)
-[![Documentation Status](https://readthedocs.org/projects/pinnicle/badge/?version=latest)](https://pinnicle.readthedocs.io/en/latest/?badge=latest)
 
 # PINNICLE
 Physics Informed Neural Networks for Ice and CLimatE
 
+[![codecov](https://codecov.io/github/enigne/PINNICLE/graph/badge.svg?token=S7REK0IKJH)](https://codecov.io/github/enigne/PINNICLE)
+[![Documentation Status](https://readthedocs.org/projects/pinnicle/badge/?version=latest)](https://pinnicle.readthedocs.io/en/latest/?badge=latest)
+
 A Python library for solving ice sheet modeling problems using a unified framework with Physics Informed Neural Networks
+
+
+---
+**NOTE**
+
+   This project is under active development.
+
+---
+**Documentation**: [pinnicle.readthedocs.io](https://pinnicle.readthedocs.io)
+
+![](docs/images/pinn.png)
+
+## Physics
+
+- Momentum Conservation (stress balance):
+  - Shelfy Stream Approximation (SSA)
+  - MOno-Layer Higher-Order (MOLHO) ice flow model
+
+- Mass Conservation (mass balance):
+  - Thickness evolution
+
+- Coupuling:
+  - stress balance + mass balance
+
+
+## Data format
+
+- `ISSM <https://issm.jpl.nasa.gov>`_ ``model()`` type, directly saved from ISSM by ``saveasstruct(md, filename)``
+- Scattered data
+
+
+## More
+
+- [Install and Setup](https://pinnicle.readthedocs.io/en/latest/installation.html#installation)
+- [An example of stress balance](https://pinnicle.readthedocs.io/en/latest/examples/pinn.ssa.html)
+- [An example of mass balance](https://pinnicle.readthedocs.io/en/latest/examples/pinn.mc.html)
+- [An example of coupling stress balance with mass balance](https://pinnicle.readthedocs.io/en/latest/examples/pinn.mcssa.html)
+