Help: Add 3.9 release note about find_dependency update

Help/release/3.9.rst

@@ -141,6 +141,11 @@ Modules
   check whether interprocedural optimization (IPO) is supported by
   the current toolchain and CMake version.
 
+* The :module:`CMakeFindDependencyMacro` module ``find_dependency`` macro
+  now forwards all arguments to the underlying :command:`find_package`
+  call.  Existing uses will continue to function as before, but callers can
+  now access the full suite of arguments that ``find_package`` accepts.
+
 * The :module:`FeatureSummary` module :command:`feature_summary` command now
   accepts the new ``DEFAULT_DESCRIPTION`` option that will print the default
   title for the selected package type.