[Backport 2.x] Add release notes for v2.18.0 #8067

Job	Run time
build-windows-macos (windows-latest, 11, -x doctest -PbuildPlatform=windows)	22m 46s
build-windows-macos (macos-13, 11)	35m 37s
build-windows-macos (windows-latest, 17, -x doctest -PbuildPlatform=windows)	22m 1s
build-windows-macos (macos-13, 17)	38m 43s
build-windows-macos (windows-latest, 21, -x doctest -PbuildPlatform=windows)	25m 26s
build-windows-macos (macos-13, 21)	34m 13s
Get-CI-Image-Tag / Get-CI-Image-Tag	3s
build-linux (11)	35m 14s
build-linux (17)	36m 42s
build-linux (21)	32m 50s
	4h 43m 35s

Provide feedback