Removed reference to ant project.

The android-project-ant directory does not exist anymore.

docs/README-android.md

@@ -6,9 +6,6 @@ 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
 ================================================================================