Documentation update: SAVANI and S40RTS

[tjhei]

Documentation of parameters uses wrong spelling for "Vs to density scaling":

$ grep -i "vs to density" -r .
./initial_conditions/S40RTS_perturbation.cc:          prm.declare_entry ("Vs to density scaling", "0.25",
./initial_conditions/S40RTS_perturbation.cc:          vs_to_density           = prm.get_double ("Vs to density scaling");
./initial_conditions/S40RTS_perturbation.cc:                                       "'vs to density scaling' parameter and the 'Thermal "
./initial_conditions/SAVANI_perturbation.cc:          prm.declare_entry ("Vs to density scaling", "0.25",
./initial_conditions/SAVANI_perturbation.cc:          vs_to_density           = prm.get_double ("Vs to density scaling");
./initial_conditions/SAVANI_perturbation.cc:                                       "'vs to density scaling' parameter and the 'Thermal "

[bjs2]

I believe I can handle this one.

[jaustermann]

I think this issue can be closed. I don't know if I'm allowed to close it ...

[gassmoeller]

Thanks. Closed.