Merge topic 'fix-project-compat_version-doc'

01f6067ce4 Help: Note when `project(COMPAT_VERSION)` was added

Acked-by: Kitware Robot <[email protected]>
Merge-request: !10858

Help/command/project.rst

@@ -88,6 +88,7 @@ The options are:
     :variable:`CMAKE_PROJECT_VERSION`.
 
 ``COMPAT_VERSION <version>``
+  .. versionadded:: 4.1
   .. note::
 
     Experimental. Gated by ``CMAKE_EXPERIMENTAL_EXPORT_PACKAGE_INFO``.