Fix a typo on pithosFS/README found by Ioannis on close
Fix a typo on pithosFS/README found by Ioannis on close

ioannisstenos/e-science,VFoteinos/e-science,ioannisstenos/e-science,VFoteinos/e-science,grnet/e-science,ibyron/e-science,grnet/e-science,KPetsas/e-science,KPetsas/e-science,ioannisstenos/e-science,grnet/e-science,VFoteinos/e-science,ibyron/e-science,ibyron/e-science,KPetsas/e-science,ibyron/e-science,grnet/e-science,ioannisstenos/e-science,ioannisstenos/e-science,KPetsas/e-science,grnet/e-science,VFoteinos/e-science,VFoteinos/e-science,ibyron/e-science,KPetsas/e-science