Merge topic 'unity-relative-paths'

f706d8064b Help: Clarify wording of UNITY_BUILD_RELOCATABLE path alternatives
20412690fb Help: Add 4.0 release note for UNITY_BUILD_RELOCATABLE
89cea1c642 Help: Document CMAKE_UNITY_BUILD_RELOCATABLE variable

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !10570