docs: update readme

Signed-off-by: nstarman <[email protected]>

README.md

@@ -1,27 +1,95 @@
-# galactic_dynamics_interoperability
+<h1 align='center'> galactic_dynamics_interoperability </h1>
+<h2 align="center"> Interoperability Between Galactic Dynamics Libraries </h2>
 
-[![Actions Status][actions-badge]][actions-link]
-[![Documentation Status][rtd-badge]][rtd-link]
+> [!WARNING] This package is under active development and is not ready for
+> public use.
+
+`galactic_dynamics_interoperability` provides tools for converting objects
+between galactic dynamics Library.
+
+## Installation
 
-[![PyPI version][pypi-version]][pypi-link]
-[![Conda-Forge][conda-badge]][conda-link]
 [![PyPI platforms][pypi-platforms]][pypi-link]
+[![PyPI version][pypi-version]][pypi-link]
+
+```bash
+pip install galactic_dynamics_interoperability
+```
+
+## Documentation
+
+[![Documentation Status][rtd-badge]][rtd-link]
+
+The main docs are in development.
+
+### Quick Start
+
+`galactic_dynamics_interoperability` provides type objects for representing
+different galactic dynamics libraries. These types are used for dispatching to
+converters:
 
+- `AbstractInteroperableLibrary` : the base class
+- `AgamaLibrary` : represents `agama`
+- `GalaLibrary` : represents `gala`
+- `GalaxLibrary` : represents `galax`
+- `GalpyLibrary` : represents `galpy`
+
+To convert potential objects between libraries use `convert_potential`. As an
+example, here is converting from a `gala` Potential to a `galax` Potential.
+
+```pycon
+>>> from galactic_dynamics_interoperability import convert_potential, GalaxLibrary
+>>> import gala.potential
+>>> from gala.units import galactic
+>>> import galax.potential
+
+>>> potential = gala.potential.KeplerPotential(m=1e11, units=galactic)
+>>> convert_potential(GalaxLibrary, potential)
+KeplerPotential(
+    units=LTMAUnitSystem( length=Unit("kpc"), ...),
+    constants=ImmutableMap({'G': ...}),
+    m_tot=ConstantParameter( value=Quantity[...](value=f64[], unit=Unit("solMass")) )
+)
+```
+
+### Q & A
+
+- _Why have the argument order `convert_potential(to, from)`, not
+  `convert_potential(from, to)`?_
+
+  This is because of how Julia structures its conversions (`convert`), from
+  which this library draws inspiration. We aim to increase interoperability
+  between galactic dynamics libraries and with the ongoing development of
+  Python-Julia bridges, Julia-wrapped-into-Python galactic dynamics libraries
+  are well within our remit.
+
+## Citation
+
+[![DOI][zenodo-badge]][zenodo-link]
+
+If you found this library to be useful and want to support the development and
+maintenance of lower-level code libraries for the scientific community, please
+consider citing this work.
+
+## Development
+
+[![codecov][codecov-badge]][codecov-link]
+[![Actions Status][actions-badge]][actions-link]
 [![GitHub Discussion][github-discussions-badge]][github-discussions-link]
 
-<!-- SPHINX-START -->
+We welcome contributions!
 
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 [github-discussions-link]:  https://github.com/GalacticDynamics/galactic_dynamics_interoperability/discussions
 [pypi-link]:                https://pypi.org/project/galactic_dynamics_interoperability/
 [pypi-platforms]:           https://img.shields.io/pypi/pyversions/galactic_dynamics_interoperability
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+[zenodo-badge]:             https://zenodo.org/badge/755708966.svg
+[zenodo-link]:              https://zenodo.org/doi/10.5281/zenodo.10850557
 
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