Revert "Docs: dwipreproc: Slice-to-volume instructions"
Revert "Docs: dwipreproc: Slice-to-volume instructions"

This reverts commit df7428a93a9d6c4ea3747f5177dac6afb0d48a0c.

The relevant dwipreproc changes to which these documentation updates apply are not yet present in the target branch.

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3