Fix CFX file support in README.md ("cad"->"cas") (#668)

Author: PProfizi

README.md

@@ -19,7 +19,7 @@ The latest version of DPF supports Ansys solver results files for:
   - Mechanical APDL (`.rst`, `.mode`, `.rfrq`, `.rdsp`)
   - LS-DYNA (`.d3plot`, `.binout`)
   - Fluent (`.cas/dat.h5`, `.flprj`)
-  - CFX (`.cad/dat.cff`, `.flprj`, `.res`)
+  - CFX (`.cas/dat.cff`, `.flprj`, `.res`)
 
 For more information on file support, see the [main page](https://dpf.docs.pyansys.com/version/stable/index.html)
 in the PyDPF-Core documentation.