docs: sphinx: add some notes about Sentry
docs: sphinx: add some notes about Sentry

Former-commit-id: 4d0aa4e14afab6e17610713067d755d0b6106221
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox