Update docs/source/userguide/export_post_processing.rst

Co-authored-by: Rémi Delaporte-Mathurin <[email protected]>

docs/source/userguide/export_post_processing.rst

@@ -61,7 +61,7 @@ The following example shows how to export the solution of a 1D problem:
 
    ...
 
-Running this should produce a file called ``mobile_conc.xdmf`` in the current directory.
+Running this should produce two files called ``mobile_conc.xdmf`` and `ˋmobile_conc.h5`` in the current directory.
 The file can then be opened in Paraview or any other software that can read XDMF files. Here are some tips for using Paraview:
 - Make sure to have the h5 file in the same directory as the XDMF file
 - Open the XDMF file then select the reader Xdmf3 Reader S