updated CHANGES for 3.2.1
updated CHANGES for 3.2.1


Former-commit-id: 6595f4bd91850eff5f7d7da0de3fbd613c971ae1
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox