MultivariateAlterationDetector: consistency between doc and code

Summary

Doc and code of the MultivariateAlterationDetector application are not consistent. See issue #1908 (closed) . The changes are :

• flip the correlation vector at the end of the computation, so that it is ordered by increasing correlation values.
• Documentation: the change maps are always sorted by increasing correlation order
• Documentation: remove the comment stating that the output change maps takes value into [-1,1], which is not true.
• Documentation: add missing end line character before bullet list.

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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Check before merging:

• All discussions are resolved
• At least 2 votes from core developers, no vote.
• The feature branch is (reasonably) up-to-date with the base branch
• Dashboard is green
• Copyright owner has signed the ORFEO ToolBox Contributor License Agreement
• Optionally, run git diff develop... -U0 --no-color | clang-format-diff.py -p1 -i on latest changes and commit