Doc: Update and deprecate ADDITIONAL_MAKE_CLEAN_FILES directory property

This extends the :prop_dir:`ADDITIONAL_MAKE_CLEAN_FILES` directory property
documentation and marks it as deprecated.  The new directory property
:prop_dir:`ADDITIONAL_CLEAN_FILES` should be used instead.

Help/prop_dir/ADDITIONAL_MAKE_CLEAN_FILES.rst

@@ -1,7 +1,17 @@
 ADDITIONAL_MAKE_CLEAN_FILES
 ---------------------------
 
-Additional files to clean during the make clean stage.
+.. deprecated:: 3.15
 
-A list of files that will be cleaned as a part of the ``make clean``
-stage.
+  Use :prop_dir:`ADDITIONAL_CLEAN_FILES` instead.
+
+Additional files to remove during the clean stage.
+
+A :ref:`;-list <CMake Language Lists>` of files that will be removed as a
+part of the ``make clean`` target.
+
+Arguments to :prop_dir:`ADDITIONAL_MAKE_CLEAN_FILES` may use
+:manual:`generator expressions <cmake-generator-expressions(7)>`.
+
+This property only works for the the Makefile generators.
+It is ignored on other generators.