Revert "Removed reference to ant project."

This reverts commit 0cad302346f95da770e5e1dc818f585c4ab4530d.

The ant directory still exists in source control

docs/README-android.md

@@ -6,6 +6,9 @@ http://trederia.blogspot.de/2017/03/building-sdl2-for-android-with-visual.html
 
 The rest of this README covers the Android gradle style build process.
 
+If you are using the older ant build process, it is no longer officially
+supported, but you can use the "android-project-ant" directory as a template.
+
 
 Requirements
 ================================================================================