Merge branch 'update/changelog-3-7release' into 'master'

Update changelog for 3.7 release

See merge request !3541

(cherry picked from commit 2e18dd92)

5cfb809d Add Examples in the Changelog for 3.7 release
99f8d74a [Changelog] Add update about Doxygen.
d1d84adf [changelog] add entry for reuse compliance
a7b03666 [changelog] Update description about Doxygen documentation.
fe732601 Add new istl linear solvers in the changelog
5b06508e fixup
1bc5421e fixup