Merge topic 'doc-config-genex-version-note'

302b22450e Help: $<CONFIG:...> supports multiple configs only since CMake 3.19

Acked-by: Kitware Robot <[email protected]>
Merge-request: !7607

Help/manual/cmake-generator-expressions.7.rst

@@ -594,6 +594,10 @@ Configuration Expressions
   expression when it is evaluated on a property of an :prop_tgt:`IMPORTED`
   target.
 
+  .. versionchanged:: 3.19
+    Multiple configurations can be specified for ``cfgs``.
+    CMake 3.18 and earlier only accepted a single configuration.
+
 .. genex:: $<OUTPUT_CONFIG:...>
 
   .. versionadded:: 3.20