Merge topic 'help-cmake_path-IS_PREFIX'

b06887b48c Merge branch 'backport-3.20-help-cmake_path-IS_PREFIX' into help-cmake_path-IS_PREFIX
4665d1e69a Help: cmake_path: fix erroneous example for IS_PREFIX
e49cbf1d44 Help: cmake_path: fix erroneous example for IS_PREFIX

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6223