Add comment documenting where format 9470 is used

Co-authored-by: npbauman <[email protected]>

Author: Copilot

src/tce/gradients/tce_gradient.F

@@ -1441,6 +1441,7 @@ logical function tce_gradient(rtdb)
  9460 format(/,1x,'Excited state root',i3,/
      1     1x,'Excitation energy / hartree =',f25.15,/
      2     1x,'                  / eV      =',f25.15)
+c     Format 9470 is used in tce_energy.F at lines 8620, 10370, and 10656
  9470 format(/,1x,A,' transition moments / hartree',/
      1     1x,'--------------------------------------------',/
      2     1x,'X',f13.7,' Y',f13.7,' Z',f13.7,/