Help: Mark features new to 3.24 in Using Dependencies Guide

The sections on FetchContent's FIND_PACKAGE_ARGS and on
Dependency Providers only apply to CMake 3.24+, so add
versionadded markers at the start of both sections.

Help/guide/using-dependencies/index.rst

@@ -304,6 +304,8 @@ with this method.
 ``FetchContent`` And ``find_package()`` Integration
 ===================================================
 
+.. versionadded:: 3.24
+
 Some dependencies support being added by either :command:`find_package` or
 :module:`FetchContent`.  Such dependencies must ensure they define the same
 namespaced targets in both installed and built-from-source scenarios.
@@ -375,6 +377,8 @@ For more advanced use cases, see the
 Dependency Providers
 ====================
 
+.. versionadded:: 3.24
+
 The preceding section discussed techniques that projects can use to specify
 their dependencies.  Ideally, the project shouldn't really care where a
 dependency comes from, as long as it provides the things it expects (often