Help/CMAKE_INSTALL_OBJECT_NAME_STRATEGY: add `versionadded` directive

Help/variable/CMAKE_INSTALL_OBJECT_NAME_STRATEGY.rst

@@ -1,6 +1,8 @@
 CMAKE_INSTALL_OBJECT_NAME_STRATEGY
 ----------------------------------
 
+.. versionadded:: 4.2
+
 Strategy to use for naming installed object files.
 
 ``CMAKE_INSTALL_OBJECT_NAME_STRATEGY`` is used to initialize the