Parallel processing documentation

[khiltunen]

Include to documentation of the limitation of mesh size to parallel processing used with the FILE-IO wrapper
Also include to documentation if parallel processing is not available on the INTERNAL wrapper (

simphony-openfoam/openfoam-interface/internal-interface/wrapper/simphonyInterface.C

Line 1108 in 590934b

FatalErrorIn("simphonyInterface:run") << "Parallel OpenFOAM Internal Interface not implemented yet" <<exit(FatalError);

)

[khiltunen]

@nathanfranklin and @jmarcelogimenez i added this isuue to remind that these should be added to documentations