DOC: improve documentation and headers of output files
DOC: improve documentation and headers of output files

Former-commit-id: fda4664acdc71021ef650874756dfaaba21ed2e4 [formerly e8feac698862a7f89095defbe607206831b6a264]
Former-commit-id: 857aac59a12f923a1e3cc4f40baf2e21e9f91139
Former-commit-id: 64c2c2a864ab260f47f70b07e88cabb0e3b93f6d
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox