Meshio optional dependency explained in Readme

Author: Fek04

pysplashsurf/README.md

@@ -10,6 +10,12 @@ pip install pysplashsurf
 ```
 Requires Python version 3.7+
 
+To install pysplashsurf directly with meshio (which allows some additional functionality), do
+```
+pip install pysplashsurf[meshio]
+```
+When meshio is installed, support for the `.bgeo` extension will be added to it, so that particle data from the `BGEOV` format can be read using meshio. Meshio is also required for the `write_to_file` method to work. The rest of the package will still work even if meshio is not installed.
+
 ## Usage
 Example to reconstruct the surface from an input file, apply some post processing methods and write the data back to a file:
 ```python

pysplashsurf/pysplashsurf/docs/source/api.rst

@@ -20,6 +20,7 @@ Methods
     par_laplacian_smoothing_normals_inplace
     reconstruct_surface
     reconstruction_pipeline
+    write_to_file
 
 Classes
 -------

pysplashsurf/pysplashsurf/docs/source/methods.rst

@@ -29,4 +29,6 @@ All methods infer float precision based on the input (32bit or 64bit).
 
 .. autofunction:: reconstruct_surface
 
-.. autofunction:: reconstruction_pipeline
+.. autofunction:: reconstruction_pipeline
+
+.. autofunction:: write_to_file