Document `@ModelAttribute` usage with native images

Closes gh-31767

framework-docs/modules/ROOT/pages/web/webflux/controller/ann-methods/modelattrib-method-args.adoc

@@ -166,4 +166,7 @@ By default, any argument that is not a simple value type (as determined by
 and is not resolved by any other argument resolver is treated as if it were annotated
 with `@ModelAttribute`.
 
-
+WARNING: When compiling to native images, implicit `@ModelAttribute` as described above does
+not allow proper ahead-of-time inference of related data binding reflection hints. As a consequence,
+it is recommended to annotate explicitly with `@ModelAttribute` method parameters for such use case
+with GraalVM.

framework-docs/modules/ROOT/pages/web/webmvc/mvc-controller/ann-methods/modelattrib-method-args.adoc

@@ -216,4 +216,7 @@ By default, any argument that is not a simple value type (as determined by
 and is not resolved by any other argument resolver is treated as if it were annotated
 with `@ModelAttribute`.
 
-
+WARNING: When compiling to native images, implicit `@ModelAttribute` as described above does
+not allow proper ahead-of-time inference of related data binding reflection hints. As a consequence,
+it is recommended to annotate explicitly with `@ModelAttribute` method parameters for such use case
+with GraalVM.