add ply to readme
@@ -16,18 +16,19 @@ There are various mesh formats available for representing unstructured meshes.
meshio can read and write all of the following and smoothly converts between them:
* [Abaqus](http://abaqus.software.polimi.it/v6.14/index.html)
- * [ANSYS msh](http://www.afs.enea.it/fluent/Public/Fluent-Doc/PDF/chp03.pdf)
- * [DOLFIN XML](http://manpages.ubuntu.com/manpages/wily/man1/dolfin-convert.1.html)
+ * [ANSYS msh](https://www.afs.enea.it/fluent/Public/Fluent-Doc/PDF/chp03.pdf)
+ * [DOLFIN XML](https://manpages.ubuntu.com/manpages/disco/man1/dolfin-convert.1.html)
* [Exodus](https://cubit.sandia.gov/public/13.2/help_manual/WebHelp/finite_element_model/exodus/block_specification.htm)
* [FLAC3D](https://www.itascacg.com/software/flac3d)
* [H5M](https://www.mcs.anl.gov/~fathom/moab-docs/h5mmain.html)
* [Kratos/MDPA](https://github.com/KratosMultiphysics/Kratos/wiki/Input-data)
* [Medit](https://people.sc.fsu.edu/~jburkardt/data/medit/medit.html)
* [MED/Salome](https://docs.salome-platform.org/latest/dev/MEDCoupling/developer/med-file.html)
- * [Nastran](http://help.autodesk.com/view/NSTRN/2019/ENU/?guid=GUID-42B54ACB-FBE3-47CA-B8FE-475E7AD91A00) (bulk data)
+ * [Nastran](https://help.autodesk.com/view/NSTRN/2019/ENU/?guid=GUID-42B54ACB-FBE3-47CA-B8FE-475E7AD91A00) (bulk data)
* [Gmsh](http://gmsh.info/doc/texinfo/gmsh.html#File-formats) (versions 2 and 4)
- * [OFF](http://segeval.cs.princeton.edu/public/off_format.html)
- * [PERMAS](http://www.intes.de)
+ * [OFF](https://segeval.cs.princeton.edu/public/off_format.html)
+ * [PERMAS](https://www.intes.de)
+ * [PLY](https://en.wikipedia.org/wiki/PLY_(file_format)<Paste>)
* [STL](https://en.wikipedia.org/wiki/STL_(file_format))
* [TetGen .node/.ele](https://wias-berlin.de/software/tetgen/fformats.html)
* [SVG](https://www.w3.org/TR/SVG/) (2D only, output only)
