Update readme

Author: BSchilperoort

README.md

@@ -1,11 +1,36 @@
 # xarray-regrid
-Regridding utility for xarray.
+Regridding utilities for xarray.
+
+Note: currently only rectilinear grids are supported.
+
+For now xarray-regrid is mostly a wrapper around `ds.interp`, however, conservative regridding is not possible with `interp`, and will need a custom solution.
 
 ## Installation
 
 ```console
 pip install xarray-regrid
 ```
 
-## Usage & benchmarks
-To see how to use xarray-regrid, see the benchmark notebooks. These also contain a comparison to more standard methods (CDO, xESMF).
+## Usage
+The xarray-regrid routines are accessed using the "regrid" accessor on an xarray Dataset:
+```py
+import xarray_regrid
+
+ds = xr.open_dataset("input_data.nc")
+ds_grid = xr.open_dataset("target_grid.nc")
+
+ds.regrid.regrid(ds_grid, method="linear")
+```
+Currently implemented are the methods linear, nearest and cubic.
+
+For examples, see the benchmark notebooks.
+
+## Benchmarks
+The benchmark notebooks contain comparisons to more standard methods (CDO, xESMF).
+
+To be able to run the notebooks, a conda environment is required (due to ESMF and CDO).
+You can install this environment using the `environment.yml` file in this repository.
+[Micromamba](https://mamba.readthedocs.io/en/latest/user_guide/micromamba.html) is a lightweight version of the much faster "mamba" conda alternative.
+
+## Planned features
+- Support conservative regridding