Add introduction to Platform-specific index page

tutorials/export/index.rst

@@ -1,5 +1,7 @@
 :allow_comments: False
 
+.. _doc_export_index:
+
 Export
 ======
 

tutorials/platform/index.rst

@@ -1,9 +1,18 @@
 :allow_comments: False
-:article_outdated: True
 
 Platform-specific
 =================
 
+Godot supports both running the editor and exporting projects on several
+platforms. Usage of the engine is generally similar across platforms, but there
+are some platform-specific considerations, which are covered in this section.
+
+.. seealso::
+
+   For platform-specific versions of the editor, see :ref:`doc_using_the_xr_editor`,
+   :ref:`doc_using_the_android_editor`, and :ref:`doc_using_the_web_editor`. For
+   exporting to specific platforms, see the :ref:`doc_export_index` section.
+
 .. toctree::
    :maxdepth: 1
    :name: toc-learn-features-platform