Negative values of `_atom_site_displace_Fourier_param.modulus` is usage examples

[vaitkus]

The ATOM_SITE_ROT_FOURIER and save_ATOM_SITE_ROT_FOURIER_PARAM categories both contain an example in which one value of the _atom_site_displace_Fourier_param.modulus data item is negative (-0.00453(2)). Not sure if this is a typo, a problem with switched value columns or something else.