elphinel.F90: fix typo

Author: Christoph Conrads

src/elphinel.F90

@@ -234,7 +234,7 @@ subroutine ElPhonNonPO_init(this, comm, struct, basis, coupling, wq, Temp, &
     logical, intent(in) :: tridiag
 
     this%descriptor = &
-        & "Electron-Phonon inelastic model for polar-optical phonons"
+        & "Electron-Phonon inelastic model for non-PO phonons"
 
     this%cart_comm = comm
     this%scba_niter = niter