Add new contributors and refer to CONTRBUTING.md in the SG
Summary
List new contributors since release 6.4 and remove contribution instruction in the software guide (link to contributing.md)
Rationale
Explain the rationale for the changes (possible link to a Request For Comments or to an issue).
Implementation Details
Classes and files
Give an overview of the implementation: main changes made to classes, files and modules. Do not paste complete diff, as it is available in the merge request already.
Applications
Describe any changes made to existing applications, or new applications that have been added.
Tests
Describe the testing strategy for new features.
Documentation
List or link documentation modifications that were made (doxygen, example, Software Guide, application documentation, CookBook).
Additional notes
List remaining open issues if any, and additional notes.
Copyright
The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement